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• How do I call up values in PHP for user input in forms (radio buttons and selects)

  - by Derek

  Ok so my admin sets to edit a book which was created. I know how to bring in the values that were initially entered via a simple text field like 'bookname'. On the edit book page the book name field stores the currently assigned 'bookname' in the field (which is what I want! :) ) However I have other field types like selects and radio button entries...I'm having trouble calling in the already set value when the book was created. For example, there is a 'booklevel' field, which I have set as radio button entries as; Hard, Normal, and Easy. When the user goes to edit the book, I'm not too sure on how to have the current value drawn up (its stored as text) and the radio button being checked. I.e. 'Normal' is checked if this is what was set when the book was created. So far I have this as the code for the adding book level: <label>Book Level:</label> <label for="booklevel1" class="radio">Hard <input type="radio" name="booklevel" id="booklevel1" value="<?php echo 'Hard'; if (isset($_POST['booklevel'])); ?>"></label> <label for="booklevel2" class="radio">Medium<input type="radio" name="booklevel" id="booklevel2" value="<?php echo 'Normal'; if (isset($_POST['booklevel'])); ?>"></label> <label for="booklevel" class="radio">Low<input type="radio" name="booklevel" id="booklevel3" value="<?php echo 'Easy'; if (isset($_POST['booklevel'])); ?>"></label> This all works fine by the way when the user adds the book... But does anyone know how in my update book form, I can draw the value of what level has been set, and have the box checked?? To draw up the values in the text fields, I'm simply using: <?php echo $row['bookname']?> I also noticed a small issue when I call up the values for my Select options. I have the drop down select field display the currently set user (to read the book!), however, the drop down menu again displays the user in the list available options to select - basically meaning 2 of the same names appear in the list! Is there a way to eliminate the value of the SELECTED option? So far my setup for this is like: <select name="user_id" id="user_id"> <option value="<?php echo $row['user_id']?>" SELECTED><?php echo $row['fullname']?></option> <?php while($row = mysql_fetch_array($result)) { ?> <option value="<?php echo $row['user_id']?>"><?php echo $row['name']?></option> <?php } ?> </select> If anyone can help me I'll be very greatful. Sorry for the incredibly long question!! :)

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• How do I filter out NaN FLOAT values in Teradata SQL?

  - by Paul Hooper

  With the Teradata database, it is possible to load values of NaN, -Inf, and +Inf into FLOAT columns through Java. Unfortunately, once those values get into the tables, they make life difficult when writing SQL that needs to filter them out. There is no IsNaN() function, nor can you "CAST ('NaN' as FLOAT)" and use an equality comparison. What I would like to do is, SELECT SUM(VAL**2) FROM DTM WHERE NOT ABS(VAL) > 1e+21 AND NOT VAL = CAST ('NaN' AS FLOAT) but that fails with error 2620, "The format or data contains a bad character.", specifically on the CAST. I've tried simply "... AND NOT VAL = 'NaN'", which also fails for a similar reason (3535, "A character string failed conversion to a numeric value."). I cannot seem to figure out how to represent NaN within the SQL statement. Even if I could represent NaN successfully in an SQL statement, I would be concerned that the comparison would fail. According to the IEEE 754 spec, NaN = NaN should evaluate to false. What I really seem to need is an IsNaN() function. Yet that function does not seem to exist.

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• Accessing and Updating Data in ASP.NET: Filtering Data Using a CheckBoxList

  Filtering Database Data with Parameters, an earlier installment in this article series, showed how to filter the data returned by ASP.NET's data source controls. In a nutshell, the data source controls can include parameterized queries whose parameter values are defined via parameter controls. For example, the SqlDataSource can include a parameterized SelectCommand, such as: SELECT * FROM Books WHERE Price > @Price. Here, @Price is a parameter; the value for a parameter can be defined declaratively using a parameter control. ASP.NET offers a variety of parameter controls, including ones that use hard-coded values, ones that retrieve values from the querystring, and ones that retrieve values from session, and others. Perhaps the most useful parameter control is the ControlParameter, which retrieves its value from a Web control on the page. Using the ControlParameter we can filter the data returned by the data source control based on the end user's input. While the ControlParameter works well with most types of Web controls, it does not work as expected with the CheckBoxList control. The ControlParameter is designed to retrieve a single property value from the specified Web control, but the CheckBoxList control does not have a property that returns all of the values of its selected items in a form that the CheckBoxList control can use. Moreover, if you are using the selected CheckBoxList items to query a database you'll quickly find that SQL does not offer out of the box functionality for filtering results based on a user-supplied list of filter criteria. The good news is that with a little bit of effort it is possible to filter data based on the end user's selections in a CheckBoxList control. This article starts with a look at how to get SQL to filter data based on a user-supplied, comma-delimited list of values. Next, it shows how to programmatically construct a comma-delimited list that represents the selected CheckBoxList values and pass that list into the SQL query. Finally, we'll explore creating a custom parameter control to handle this logic declaratively. Read on to learn more! Read More >

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• Elusive race condition in Java

  - by nasufara

  I am creating a graphing calculator. In an attempt to squeeze some more performance out of it, I added some multithreaded to the line calculator. Essentially what my current implementation does is construct a thread-safe Queue of X values, then start however many threads it needs, each one calculating a point on the line using the queue to get its values, and then ordering the points using a HashMap when the calculations are done. This implementation works great, and that's not where my race condition is (merely some background info). In examining the performance results from this, I found that the HashMap is a performance bottleneck, since I do that synchronously on one thread. So I figured that ordering each point as its calculated would work best. I tried a PriorityQueue, but that was slower than the HashMap. I ended up creating an algorithm that essentially works like this: I construct a list of X values to calculate, like in my current algorithm. I then copy that list of values into another class, unimaginatively and temporarily named BlockingList, which is responsible for ordering the points as they are calculated. BlockingList contains a put() method, which takes in two BigDecimals as parameters, the first the X value, the second the calculated Y value. put() will only accept a value if the X value is the next one on the list to be accepted in the list of X values, and will block until another thread gives it the next excepted value. For example, since that can be confusing, say I have two threads, Thread-1 and Thread-2. Thread-2 gets the X value 10.0 from the values queue, and Thread-1 gets 9.0. However, Thread-1 completes its calculations first, and calls put() before Thread-2 does. Because BlockingList is expecting to get 10.0 first, and not 9.0, it will block on Thread-1 until Thread-2 finishes and calls put(). Once Thread-2 gives BlockingList 10.0, it notify()s all waiting threads, and expects 9.0 next. This continues until BlockingList gets all of its expected values. (I apologise if that was hard to follow, if you need more clarification, just ask.) As expected by the question title, there is a race condition in here. If I run it without any System.out.printlns, it will sometimes lock because of conflicting wait() and notifyAll()s, but if I put a println in, it will run great. A small implementation of this is included below, and exhibits the same behavior: import java.math.BigDecimal; import java.util.concurrent.ConcurrentLinkedQueue; public class Example { public static void main(String[] args) throws InterruptedException { // Various scaling values, determined based on the graph size // in the real implementation BigDecimal xMax = new BigDecimal(10); BigDecimal xStep = new BigDecimal(0.05); // Construct the values list, from -10 to 10 final ConcurrentLinkedQueue<BigDecimal> values = new ConcurrentLinkedQueue<BigDecimal>(); for (BigDecimal i = new BigDecimal(-10); i.compareTo(xMax) <= 0; i = i.add(xStep)) { values.add(i); } // Contains the calculated values final BlockingList list = new BlockingList(values); for (int i = 0; i < 4; i++) { new Thread() { public void run() { BigDecimal x; // Keep looping until there are no more values while ((x = values.poll()) != null) { PointPair pair = new PointPair(); pair.realX = x; try { list.put(pair); } catch (Exception ex) { ex.printStackTrace(); } } } }.start(); } } private static class PointPair { public BigDecimal realX; } private static class BlockingList { private final ConcurrentLinkedQueue<BigDecimal> _values; private final ConcurrentLinkedQueue<PointPair> _list = new ConcurrentLinkedQueue<PointPair>(); public BlockingList(ConcurrentLinkedQueue<BigDecimal> expectedValues) throws InterruptedException { // Copy the values into a new queue BigDecimal[] arr = expectedValues.toArray(new BigDecimal[0]); _values = new ConcurrentLinkedQueue<BigDecimal>(); for (BigDecimal dec : arr) { _values.add(dec); } } public void put(PointPair item) throws InterruptedException { while (item.realX.compareTo(_values.peek()) != 0) { synchronized (this) { // Block until someone enters the next desired value wait(); } } _list.add(item); _values.poll(); synchronized (this) { notifyAll(); } } } } My question is can anybody help me find the threading error? Thanks!

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• Accessing and Updating Data in ASP.NET: Filtering Data Using a CheckBoxList

  Filtering Database Data with Parameters, an earlier installment in this article series, showed how to filter the data returned by ASP.NET's data source controls. In a nutshell, the data source controls can include parameterized queries whose parameter values are defined via parameter controls. For example, the SqlDataSource can include a parameterized SelectCommand, such as: SELECT * FROM Books WHERE Price > @Price. Here, @Price is a parameter; the value for a parameter can be defined declaratively using a parameter control. ASP.NET offers a variety of parameter controls, including ones that use hard-coded values, ones that retrieve values from the querystring, and ones that retrieve values from session, and others. Perhaps the most useful parameter control is the ControlParameter, which retrieves its value from a Web control on the page. Using the ControlParameter we can filter the data returned by the data source control based on the end user's input. While the ControlParameter works well with most types of Web controls, it does not work as expected with the CheckBoxList control. The ControlParameter is designed to retrieve a single property value from the specified Web control, but the CheckBoxList control does not have a property that returns all of the values of its selected items in a form that the CheckBoxList control can use. Moreover, if you are using the selected CheckBoxList items to query a database you'll quickly find that SQL does not offer out of the box functionality for filtering results based on a user-supplied list of filter criteria. The good news is that with a little bit of effort it is possible to filter data based on the end user's selections in a CheckBoxList control. This article starts with a look at how to get SQL to filter data based on a user-supplied, comma-delimited list of values. Next, it shows how to programmatically construct a comma-delimited list that represents the selected CheckBoxList values and pass that list into the SQL query. Finally, we'll explore creating a custom parameter control to handle this logic declaratively. Read on to learn more! Read More >

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• Enum.HasFlag

  - by Scott Dorman

  An enumerated type, also called an enumeration (or just an enum for short), is simply a way to create a numeric type restricted to a predetermined set of valid values with meaningful names for those values. While most enumerations represent discrete values, or well-known combinations of those values, sometimes you want to combine values in an arbitrary fashion. These enumerations are known as flags enumerations because the values represent flags which can be set or unset. To combine multiple enumeration values, you use the logical OR operator. For example, consider the following: public enum FileAccess { None = 0, Read = 1, Write = 2, }   class Program { static void Main(string[] args) { FileAccess access = FileAccess.Read | FileAccess.Write; Console.WriteLine(access); } } The output of this simple console application is: The value 3 is the numeric value associated with the combination of FileAccess.Read and FileAccess.Write. Clearly, this isn’t the best representation. What you really want is for the output to look like: To achieve this result, you simply add the Flags attribute to the enumeration. The Flags attribute changes how the string representation of the enumeration value is displayed when using the ToString() method. Although the .NET Framework does not require it, enumerations that will be used to represent flags should be decorated with the Flags attribute since it provides a clear indication of intent. One “problem” with Flags enumerations is determining when a particular flag is set. The code to do this isn’t particularly difficult, but unless you use it regularly it can be easy to forget. To test if the access variable has the FileAccess.Read flag set, you would use the following code: (access & FileAccess.Read) == FileAccess.Read Starting with .NET 4, a HasFlag static method has been added to the Enum class which allows you to easily perform these tests: access.HasFlag(FileAccess.Read) This method follows one of the “themes” for the .NET Framework 4, which is to simplify and reduce the amount of boilerplate code like this you must write. Technorati Tags: .NET,C# 4

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• The blocking nature of aggregates

  - by Rob Farley

  I wrote a post recently about how query tuning isn’t just about how quickly the query runs – that if you have something (such as SSIS) that is consuming your data (and probably introducing a bottleneck), then it might be more important to have a query which focuses on getting the first bit of data out. You can read that post here.  In particular, we looked at two operators that could be used to ensure that a query returns only Distinct rows. and The Sort operator pulls in all the data, sorts it (discarding duplicates), and then pushes out the remaining rows. The Hash Match operator performs a Hashing function on each row as it comes in, and then looks to see if it’s created a Hash it’s seen before. If not, it pushes the row out. The Sort method is quicker, but has to wait until it’s gathered all the data before it can do the sort, and therefore blocks the data flow. But that was my last post. This one’s a bit different. This post is going to look at how Aggregate functions work, which ties nicely into this month’s T-SQL Tuesday. I’ve frequently explained about the fact that DISTINCT and GROUP BY are essentially the same function, although DISTINCT is the poorer cousin because you have less control over it, and you can’t apply aggregate functions. Just like the operators used for Distinct, there are different flavours of Aggregate operators – coming in blocking and non-blocking varieties. The example I like to use to explain this is a pile of playing cards. If I’m handed a pile of cards and asked to count how many cards there are in each suit, it’s going to help if the cards are already ordered. Suppose I’m playing a game of Bridge, I can easily glance at my hand and count how many there are in each suit, because I keep the pile of cards in order. Moving from left to right, I could tell you I have four Hearts in my hand, even before I’ve got to the end. By telling you that I have four Hearts as soon as I know, I demonstrate the principle of a non-blocking operation. This is known as a Stream Aggregate operation. It requires input which is sorted by whichever columns the grouping is on, and it will release a row as soon as the group changes – when I encounter a Spade, I know I don’t have any more Hearts in my hand. Alternatively, if the pile of cards are not sorted, I won’t know how many Hearts I have until I’ve looked through all the cards. In fact, to count them, I basically need to put them into little piles, and when I’ve finished making all those piles, I can count how many there are in each. Because I don’t know any of the final numbers until I’ve seen all the cards, this is blocking. This performs the aggregate function using a Hash Match. Observant readers will remember this from my Distinct example. You might remember that my earlier Hash Match operation – used for Distinct Flow – wasn’t blocking. But this one is. They’re essentially doing a similar operation, applying a Hash function to some data and seeing if the set of values have been seen before, but before, it needs more information than the mere existence of a new set of values, it needs to consider how many of them there are. A lot is dependent here on whether the data coming out of the source is sorted or not, and this is largely determined by the indexes that are being used. If you look in the Properties of an Index Scan, you’ll be able to see whether the order of the data is required by the plan. A property called Ordered will demonstrate this. In this particular example, the second plan is significantly faster, but is dependent on having ordered data. In fact, if I force a Stream Aggregate on unordered data (which I’m doing by telling it to use a different index), a Sort operation is needed, which makes my plan a lot slower. This is all very straight-forward stuff, and information that most people are fully aware of. I’m sure you’ve all read my good friend Paul White (@sql_kiwi)’s post on how the Query Optimizer chooses which type of aggregate function to apply. But let’s take a look at SQL Server Integration Services. SSIS gives us a Aggregate transformation for use in Data Flow Tasks, but it’s described as Blocking. The definitive article on Performance Tuning SSIS uses Sort and Aggregate as examples of Blocking Transformations. I’ve just shown you that Aggregate operations used by the Query Optimizer are not always blocking, but that the SSIS Aggregate component is an example of a blocking transformation. But is it always the case? After all, there are plenty of SSIS Performance Tuning talks out there that describe the value of sorted data in Data Flow Tasks, describing the IsSorted property that can be set through the Advanced Editor of your Source component. And so I set about testing the Aggregate transformation in SSIS, to prove for sure whether providing Sorted data would let the Aggregate transform behave like a Stream Aggregate. (Of course, I knew the answer already, but it helps to be able to demonstrate these things). A query that will produce a million rows in order was in order. Let me rephrase. I used a query which produced the numbers from 1 to 1000000, in a single field, ordered. The IsSorted flag was set on the source output, with the only column as SortKey 1. Performing an Aggregate function over this (counting the number of rows per distinct number) should produce an additional column with 1 in it. If this were being done in T-SQL, the ordered data would allow a Stream Aggregate to be used. In fact, if the Query Optimizer saw that the field had a Unique Index on it, it would be able to skip the Aggregate function completely, and just insert the value 1. This is a shortcut I wouldn’t be expecting from SSIS, but certainly the Stream behaviour would be nice. Unfortunately, it’s not the case. As you can see from the screenshots above, the data is pouring into the Aggregate function, and not being released until all million rows have been seen. It’s not doing a Stream Aggregate at all. This is expected behaviour. (I put that in bold, because I want you to realise this.) An SSIS transformation is a piece of code that runs. It’s a physical operation. When you write T-SQL and ask for an aggregation to be done, it’s a logical operation. The physical operation is either a Stream Aggregate or a Hash Match. In SSIS, you’re telling the system that you want a generic Aggregation, that will have to work with whatever data is passed in. I’m not saying that it wouldn’t be possible to make a sometimes-blocking aggregation component in SSIS. A Custom Component could be created which could detect whether the SortKeys columns of the input matched the Grouping columns of the Aggregation, and either call the blocking code or the non-blocking code as appropriate. One day I’ll make one of those, and publish it on my blog. I’ve done it before with a Script Component, but as Script components are single-use, I was able to handle the data knowing everything about my data flow already. As per my previous post – there are a lot of aspects in which tuning SSIS and tuning execution plans use similar concepts. In both situations, it really helps to have a feel for what’s going on behind the scenes. Considering whether an operation is blocking or not is extremely relevant to performance, and that it’s not always obvious from the surface. In a future post, I’ll show the impact of blocking v non-blocking and synchronous v asynchronous components in SSIS, using some of LobsterPot’s Script Components and Custom Components as examples. When I get that sorted, I’ll make a Stream Aggregate component available for download.

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• The blocking nature of aggregates

  - by Rob Farley

  I wrote a post recently about how query tuning isn’t just about how quickly the query runs – that if you have something (such as SSIS) that is consuming your data (and probably introducing a bottleneck), then it might be more important to have a query which focuses on getting the first bit of data out. You can read that post here.  In particular, we looked at two operators that could be used to ensure that a query returns only Distinct rows. and The Sort operator pulls in all the data, sorts it (discarding duplicates), and then pushes out the remaining rows. The Hash Match operator performs a Hashing function on each row as it comes in, and then looks to see if it’s created a Hash it’s seen before. If not, it pushes the row out. The Sort method is quicker, but has to wait until it’s gathered all the data before it can do the sort, and therefore blocks the data flow. But that was my last post. This one’s a bit different. This post is going to look at how Aggregate functions work, which ties nicely into this month’s T-SQL Tuesday. I’ve frequently explained about the fact that DISTINCT and GROUP BY are essentially the same function, although DISTINCT is the poorer cousin because you have less control over it, and you can’t apply aggregate functions. Just like the operators used for Distinct, there are different flavours of Aggregate operators – coming in blocking and non-blocking varieties. The example I like to use to explain this is a pile of playing cards. If I’m handed a pile of cards and asked to count how many cards there are in each suit, it’s going to help if the cards are already ordered. Suppose I’m playing a game of Bridge, I can easily glance at my hand and count how many there are in each suit, because I keep the pile of cards in order. Moving from left to right, I could tell you I have four Hearts in my hand, even before I’ve got to the end. By telling you that I have four Hearts as soon as I know, I demonstrate the principle of a non-blocking operation. This is known as a Stream Aggregate operation. It requires input which is sorted by whichever columns the grouping is on, and it will release a row as soon as the group changes – when I encounter a Spade, I know I don’t have any more Hearts in my hand. Alternatively, if the pile of cards are not sorted, I won’t know how many Hearts I have until I’ve looked through all the cards. In fact, to count them, I basically need to put them into little piles, and when I’ve finished making all those piles, I can count how many there are in each. Because I don’t know any of the final numbers until I’ve seen all the cards, this is blocking. This performs the aggregate function using a Hash Match. Observant readers will remember this from my Distinct example. You might remember that my earlier Hash Match operation – used for Distinct Flow – wasn’t blocking. But this one is. They’re essentially doing a similar operation, applying a Hash function to some data and seeing if the set of values have been seen before, but before, it needs more information than the mere existence of a new set of values, it needs to consider how many of them there are. A lot is dependent here on whether the data coming out of the source is sorted or not, and this is largely determined by the indexes that are being used. If you look in the Properties of an Index Scan, you’ll be able to see whether the order of the data is required by the plan. A property called Ordered will demonstrate this. In this particular example, the second plan is significantly faster, but is dependent on having ordered data. In fact, if I force a Stream Aggregate on unordered data (which I’m doing by telling it to use a different index), a Sort operation is needed, which makes my plan a lot slower. This is all very straight-forward stuff, and information that most people are fully aware of. I’m sure you’ve all read my good friend Paul White (@sql_kiwi)’s post on how the Query Optimizer chooses which type of aggregate function to apply. But let’s take a look at SQL Server Integration Services. SSIS gives us a Aggregate transformation for use in Data Flow Tasks, but it’s described as Blocking. The definitive article on Performance Tuning SSIS uses Sort and Aggregate as examples of Blocking Transformations. I’ve just shown you that Aggregate operations used by the Query Optimizer are not always blocking, but that the SSIS Aggregate component is an example of a blocking transformation. But is it always the case? After all, there are plenty of SSIS Performance Tuning talks out there that describe the value of sorted data in Data Flow Tasks, describing the IsSorted property that can be set through the Advanced Editor of your Source component. And so I set about testing the Aggregate transformation in SSIS, to prove for sure whether providing Sorted data would let the Aggregate transform behave like a Stream Aggregate. (Of course, I knew the answer already, but it helps to be able to demonstrate these things). A query that will produce a million rows in order was in order. Let me rephrase. I used a query which produced the numbers from 1 to 1000000, in a single field, ordered. The IsSorted flag was set on the source output, with the only column as SortKey 1. Performing an Aggregate function over this (counting the number of rows per distinct number) should produce an additional column with 1 in it. If this were being done in T-SQL, the ordered data would allow a Stream Aggregate to be used. In fact, if the Query Optimizer saw that the field had a Unique Index on it, it would be able to skip the Aggregate function completely, and just insert the value 1. This is a shortcut I wouldn’t be expecting from SSIS, but certainly the Stream behaviour would be nice. Unfortunately, it’s not the case. As you can see from the screenshots above, the data is pouring into the Aggregate function, and not being released until all million rows have been seen. It’s not doing a Stream Aggregate at all. This is expected behaviour. (I put that in bold, because I want you to realise this.) An SSIS transformation is a piece of code that runs. It’s a physical operation. When you write T-SQL and ask for an aggregation to be done, it’s a logical operation. The physical operation is either a Stream Aggregate or a Hash Match. In SSIS, you’re telling the system that you want a generic Aggregation, that will have to work with whatever data is passed in. I’m not saying that it wouldn’t be possible to make a sometimes-blocking aggregation component in SSIS. A Custom Component could be created which could detect whether the SortKeys columns of the input matched the Grouping columns of the Aggregation, and either call the blocking code or the non-blocking code as appropriate. One day I’ll make one of those, and publish it on my blog. I’ve done it before with a Script Component, but as Script components are single-use, I was able to handle the data knowing everything about my data flow already. As per my previous post – there are a lot of aspects in which tuning SSIS and tuning execution plans use similar concepts. In both situations, it really helps to have a feel for what’s going on behind the scenes. Considering whether an operation is blocking or not is extremely relevant to performance, and that it’s not always obvious from the surface. In a future post, I’ll show the impact of blocking v non-blocking and synchronous v asynchronous components in SSIS, using some of LobsterPot’s Script Components and Custom Components as examples. When I get that sorted, I’ll make a Stream Aggregate component available for download.

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• How can I select values from different rows depending on the most recent entry date, all for the sam

  - by user321185

  Basically I have a table which is used to hold employee work wear details. It is formed of the columns: EmployeeID, CostCentre, AssociateLevel, IssueDate, TrouserSize, TrouserLength, TopSize & ShoeSize. An employee can be assigned a pair of trousers, a top and shoes at the same time or only one or two pieces of clothing. As we all know peoples sizes and employee levels can change which is why I need help really. Different types of employees (associatelevels) require different colours of clothing but you can ignore this part. Everytime an employee receives an item of clothing a new row will be inserted into the table with an input date. I need to be able to select the most recent clothes size for each item of clothing for each employee. It is not necessary for all the columns to hold values because an employee could receive trousers or poloshirts at different times in the year. So for example if employee '54664LSS' was given a pair of 'XL' trousers and a 'L' top on 24/03/11 but then received a 'M' top on 26/05/10. The input of these items would be help on two different rows obviously. So if I wanted to select the most recent clothing for each clothes category. Then the values of the 'M' sized top and the 'L' sized trousers would need to be returned. Any help would be greatly appreciated as I'm pretty stuck :(. Thanks.

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• How to write Sql or LinqToSql for this scenario?

  - by Mike108

  How to write Sql or LinqToSql for this scenario? A table has the following data: Id UserName Price Date Status 1 Mike 2 2010-4-25 0:00:00 Success 2 Mike 3 2010-4-25 0:00:00 Fail 3 Mike 2 2010-4-25 0:00:00 Success 4 Lily 5 2010-4-25 0:00:00 Success 5 Mike 1 2010-4-25 0:00:00 Fail 6 Lily 5 2010-4-25 0:00:00 Success 7 Mike 2 2010-4-26 0:00:00 Success 8 Lily 5 2010-4-26 0:00:00 Fail 9 Lily 2 2010-4-26 0:00:00 Success 10 Lily 1 2010-4-26 0:00:00 Fail I want to get the summary result from the data, the result should be: UserName Date TotalPrice TotalRecord SuccessRecord FailRecord Mike 2010-04-25 8 4 2 2 Lily 2010-04-25 10 2 2 0 Mike 2010-04-26 2 1 1 0 Lily 2010-04-26 8 3 1 2 The TotalPrice is the sum(Price) groupby UserName and Date The TotalRecord is the count(*) groupby UserName and Date The SuccessRecord is the count(*) groupby UserName and Date where Status='Success' The FailRecord is the count(*) groupby UserName and Date where Status='Fail' The TotalRecord = SuccessRecord + FailRecord The sql server 2005 database script is: /****** Object: Table [dbo].[Pay] Script Date: 04/28/2010 22:23:42 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Pay]') AND type in (N'U')) BEGIN CREATE TABLE [dbo].[Pay]( [Id] [int] IDENTITY(1,1) NOT NULL, [UserName] [nvarchar](50) COLLATE Chinese_PRC_CI_AS NULL, [Price] [int] NULL, [Date] [datetime] NULL, [Status] [nvarchar](50) COLLATE Chinese_PRC_CI_AS NULL, CONSTRAINT [PK_Pay] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ) END GO SET IDENTITY_INSERT [dbo].[Pay] ON INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (1, N'Mike', 2, CAST(0x00009D6300000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (2, N'Mike', 3, CAST(0x00009D6300000000 AS DateTime), N'Fail') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (3, N'Mike', 2, CAST(0x00009D6300000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (4, N'Lily', 5, CAST(0x00009D6300000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (5, N'Mike', 1, CAST(0x00009D6300000000 AS DateTime), N'Fail') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (6, N'Lily', 5, CAST(0x00009D6300000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (7, N'Mike', 2, CAST(0x00009D6400000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (8, N'Lily', 5, CAST(0x00009D6400000000 AS DateTime), N'Fail') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (9, N'Lily', 2, CAST(0x00009D6400000000 AS DateTime), N'Success') INSERT [dbo].[Pay] ([Id], [UserName], [Price], [Date], [Status]) VALUES (10, N'Lily', 1, CAST(0x00009D6400000000 AS DateTime), N'Fail') SET IDENTITY_INSERT [dbo].[Pay] OFF

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• sql-server: Can I update two table with Single Query?

  - by RedsDevils

  How can I write single UPDATE query to change value of COL1 to ‘X’ if COL2 < 10 otherwise change it to ‘Y’, where the following two tables are linked by ID CREATE TABLE TEMP(ID TINYINT, COL1 CHAR(1)) INSERT INTO TEMP(ID,COL1) VALUES (1,'A') INSERT INTO TEMP(ID,COL1) VALUES (2,'B') INSERT INTO TEMP(ID,COL1) VALUES (11,'A') INSERT INTO TEMP(ID,COL1) VALUES (17,'B') CREATE TABLE TEMP2(ID TINYINT, COL2 TINYINT) INSERT INTO TEMP2(ID,COL2) VALUES (1,1) INSERT INTO TEMP2(ID,COL2) VALUES (2,5) INSERT INTO TEMP2(ID,COL2) VALUES (11,10) INSERT INTO TEMP2(ID,COL2) VALUES (17,15) Thanks in advance!

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• Optimizing MySql query to avoid using "Using filesort"

  - by usef_ksa

  I need your help to optimize the query to avoid using "Using filesort".The job of the query is to select all the articles that belongs to specific tag. The query is: "select title from tag,article where tag='Riyad' AND tag.article_id=article.id order by tag.article_id". the tables structure are the following: Tag table CREATE TABLE `tag` ( `tag` VARCHAR( 30 ) NOT NULL , `article_id` INT NOT NULL , INDEX ( `tag` ) ) ENGINE = MYISAM ; Article table CREATE TABLE `article` ( `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY , `title` VARCHAR( 60 ) NOT NULL ) ENGINE = MYISAM Sample data INSERT INTO `article` VALUES (1, 'About Riyad'); INSERT INTO `article` VALUES (2, 'About Newyork'); INSERT INTO `article` VALUES (3, 'About Paris'); INSERT INTO `article` VALUES (4, 'About London'); INSERT INTO `tag` VALUES ('Riyad', 1); INSERT INTO `tag` VALUES ('Saudia', 1); INSERT INTO `tag` VALUES ('Newyork', 2); INSERT INTO `tag` VALUES ('USA', 2); INSERT INTO `tag` VALUES ('Paris', 3); INSERT INTO `tag` VALUES ('France', 3);

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• Proving that the distance values extracted in Dijkstra's algorithm is non-decreasing?

  - by Gail

  I'm reviewing my old algorithms notes and have come across this proof. It was from an assignment I had and I got it correct, but I feel that the proof certainly lacks. The question is to prove that the distance values taken from the priority queue in Dijkstra's algorithm is a non-decreasing sequence. My proof goes as follows: Proof by contradiction. Fist, assume that we pull a vertex from Q with d-value 'i'. Next time, we pull a vertex with d-value 'j'. When we pulled i, we have finalised our d-value and computed the shortest-path from the start vertex, s, to i. Since we have positive edge weights, it is impossible for our d-values to shrink as we add vertices to our path. If after pulling i from Q, we pull j with a smaller d-value, we may not have a shortest path to i, since we may be able to reach i through j. However, we have already computed the shortest path to i. We did not check a possible path. We no longer have a guaranteed path. Contradiction.

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• T-SQL - Left Outer Joins - Fileters in the where clause versus the on clause.

  - by Greg Potter

  I am trying to compare two tables to find rows in each table that is not in the other. Table 1 has a groupby column to create 2 sets of data within table one. groupby number ----------- ----------- 1 1 1 2 2 1 2 2 2 4 Table 2 has only one column. number ----------- 1 3 4 So Table 1 has the values 1,2,4 in group 2 and Table 2 has the values 1,3,4. I expect the following result when joining for Group 2: `Table 1 LEFT OUTER Join Table 2` T1_Groupby T1_Number T2_Number ----------- ----------- ----------- 2 2 NULL `Table 2 LEFT OUTER Join Table 1` T1_Groupby T1_Number T2_Number ----------- ----------- ----------- NULL NULL 3 The only way I can get this to work is if I put a where clause for the first join: PRINT 'Table 1 LEFT OUTER Join Table 2, with WHERE clause' select table1.groupby as [T1_Groupby], table1.number as [T1_Number], table2.number as [T2_Number] from table1 LEFT OUTER join table2 --****************************** on table1.number = table2.number --****************************** WHERE table1.groupby = 2 AND table2.number IS NULL and a filter in the ON for the second: PRINT 'Table 2 LEFT OUTER Join Table 1, with ON clause' select table1.groupby as [T1_Groupby], table1.number as [T1_Number], table2.number as [T2_Number] from table2 LEFT OUTER join table1 --****************************** on table2.number = table1.number AND table1.groupby = 2 --****************************** WHERE table1.number IS NULL Can anyone come up with a way of not using the filter in the on clause but in the where clause? The context of this is I have a staging area in a database and I want to identify new records and records that have been deleted. The groupby field is the equivalent of a batchid for an extract and I am comparing the latest extract in a temp table to a the batch from yesterday stored in a partioneds table, which also has all the previously extracted batches as well. Code to create table 1 and 2: create table table1 (number int, groupby int) create table table2 (number int) insert into table1 (number, groupby) values (1, 1) insert into table1 (number, groupby) values (2, 1) insert into table1 (number, groupby) values (1, 2) insert into table2 (number) values (1) insert into table1 (number, groupby) values (2, 2) insert into table2 (number) values (3) insert into table1 (number, groupby) values (4, 2) insert into table2 (number) values (4)

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• How do I get many, but not all, property values from View to Presenter in WebFormsMvp?

  - by andrej351

  Hey there, What is the best way to get a number of property values of a business object from the View to the Presenter in a WebFormsMvp page? Here is what i propose: The scenario is, I have a business object called Quote which i would like to load form the database, edit and then save. The Quote class has heaps of properties on it. The form is concerned with about 20 of these properties. I have existing methods to load/save a Quote object to/from the database. I now need to wire this all together. So, in the View_Load handler on my presenter i intend to do something like this: public void View_Load(object sender, EventArgs e) { View.Model.Quote = quoteService.Read(quoteId); } And then bind all my controls as follows: <asp:TextBox ID="TotalPriceTextBox" runat="server" Text="<%# Model.Quote.TotalPrice %>" /> All good, the data is on the screen. The user then makes a bunch of changes and hits a "Submit" button. Here is where I'm unsure. I create a class called QuoteEventArgs exposing the 20 properties the form is able to edit. When the View raises the Submit button's event, I set these properties to the values of the controls in the code behind. Then raise the event for the presenter to respond to. The presenter re-loads the Quote object from the database, sets all the properties and saves it to the database. Is this the right way to do this? If not, what is? Cheers, Andrej.

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• C/C++: Passing a structure by value, with another structure as one of its members, changes values of

  - by jellyfisharepretty

  Sorry for the confusing title, but it basically says it all. Here's the structures I'm using (found in OpenCV) : struct CV_EXPORTS CvRTParams : public CvDTreeParams { bool calc_var_importance; int nactive_vars; CvTermCriteria term_crit; CvRTParams() : CvDTreeParams( 5, 10, 0, false, 10, 0, false, false, 0 ), calc_var_importance(false), nactive_vars(0) { term_crit = cvTermCriteria( CV_TERMCRIT_ITER+CV_TERMCRIT_EPS, 50, 0.1 ); } } and typedef struct CvTermCriteria { int type; int max_iter; double epsilon; } CvTermCriteria; CV_INLINE CvTermCriteria cvTermCriteria( int type, int max_iter, double epsilon ) { CvTermCriteria t; t.type = type; t.max_iter = max_iter; t.epsilon = (float)epsilon; return t; } Now, I initialize a CvRTParams structure and set values for its members : CvRTParams params; params.max_depth = 8; params.min_sample_count = 10; params.regression_accuracy = 0; params.use_surrogates = false; params.max_categories = 10; params.priors = priors; params.calc_var_importance = true; params.nactive_vars = 9; params.term_crit.max_iter = 33; params.term_crit.epsilon = 0.1; params.term_crit.type = 3; Then call a function of an object, taking params in as a parameter : CvRTrees* rt = new CvRTrees; rt->train(t, CV_ROW_SAMPLE, r, 0, 0, var_type, 0, params) What happens now ? Values of... params.term_crit.max_iter params.term_crit.epsilon params.term_crit.type have changed ! They are no longer 33, 0.1 and 3, but something along the lines of 3, 7.05541e-313 and 4, and this, for the whole duration of the CvRtrees::train() function...

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• How to list all duplicated rows which may include NULL columns?

  - by Yousui

  Hi guys, I have a problem of listing duplicated rows that include NULL columns. Lemme show my problem first. USE [tempdb]; GO IF OBJECT_ID(N'dbo.t') IS NOT NULL BEGIN DROP TABLE dbo.t END GO CREATE TABLE dbo.t ( a NVARCHAR(8), b NVARCHAR(8) ); GO INSERT t VALUES ('a', 'b'); INSERT t VALUES ('a', 'b'); INSERT t VALUES ('a', 'b'); INSERT t VALUES ('c', 'd'); INSERT t VALUES ('c', 'd'); INSERT t VALUES ('c', 'd'); INSERT t VALUES ('c', 'd'); INSERT t VALUES ('e', NULL); INSERT t VALUES (NULL, NULL); INSERT t VALUES (NULL, NULL); INSERT t VALUES (NULL, NULL); INSERT t VALUES (NULL, NULL); GO Now I want to show all rows that have other rows duplicated with them, I use the following query. SELECT a, b FROM dbo.t GROUP BY a, b HAVING count(*) > 1 which will give us the result: a b -------- -------- NULL NULL a b c d Now if I want to list all rows that make contribution to duplication, I use this query: WITH duplicate (a, b) AS ( SELECT a, b FROM dbo.t GROUP BY a, b HAVING count(*) > 1 ) SELECT dbo.t.a, dbo.t.b FROM dbo.t INNER JOIN duplicate ON (dbo.t.a = duplicate.a AND dbo.t.b = duplicate.b) Which will give me the result: a b -------- -------- a b a b a b c d c d c d c d As you can see, all rows include NULLs are filtered. The reason I thought is that I use equal sign to test the condition(dbo.t.a = duplicate.a AND dbo.t.b = duplicate.b), and NULLs cannot be compared use equal sign. So, in order to include rows that include NULLs in it in the last result, I have change the aforementioned query to WITH duplicate (a, b) AS ( SELECT a, b FROM dbo.t GROUP BY a, b HAVING count(*) > 1 ) SELECT dbo.t.a, dbo.t.b FROM dbo.t INNER JOIN duplicate ON (dbo.t.a = duplicate.a AND dbo.t.b = duplicate.b) OR (dbo.t.a IS NULL AND duplicate.a IS NULL AND dbo.t.b = duplicate.b) OR (dbo.t.b IS NULL AND duplicate.b IS NULL AND dbo.t.a = duplicate.a) OR (dbo.t.a IS NULL AND duplicate.a IS NULL AND dbo.t.b IS NULL AND duplicate.b IS NULL) And this query will give me the answer as I wanted: a b -------- -------- NULL NULL NULL NULL NULL NULL NULL NULL a b a b a b c d c d c d c d Now my question is, as you can see, this query just include two columns, in order to include NULLs in the last result, you have to use many condition testing statements in the query. As the column number increasing, the condition testing statements you need in your query is increasing astonishingly. How can I solve this problem? Great thanks.

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• SQL query to translate a list of numbers matched against several ranges, to a list of values

  - by Claes Mogren

  I need to convert a list of numbers that fall within certain ranges into a list of values, ordered by a priority column. The table has the following values: | YEAR | R_MIN | R_MAX | VAL | PRIO | ------------------------------------ 2010 18000 90100 52 6 2010 240000 240099 82 3 2010 250000 259999 50 5 2010 260000 260010 92 1 2010 330000 330010 73 4 2010 330011 370020 50 5 2010 380000 380050 84 2 The ranges will be different for different years. The ranges within one year will never overlap. The input will be a year and a list of numbers that might fall within one these ranges. The list of input number will be small, 1 to 10 numbers. Example of input numbers: (20000, 240004, 375000, 255000) With that input I would like to get a list ordered by the priority column, or a single value: 82 50 52 The only value I'm interested in here is 82, so UNIQUE and MAX_RESULTS=1 would do. It can easily be done with one query per number, and then sorting it in the Java code, but I would prefer to do it in a single SQL query. What SQL query, to be run in an Oracle database, would give me the desired result?

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• Image jQuery scroller in a container. (like facebook cropper) can't get values of position.

  - by Stefan

  Hey all. Having a reallllll mind pain. I have a php image uploader which is all good and sotring the file and the jquery ajax is returning the image in an ammended html div with a div set up like this: #crop-holder { width:80px; height:80px; margin:10px 10px 20px 10px; border:1px #c0c0c0 solid; overflow:hidden; cursor:move; } The image is viewing fine and I am using the jquery scrollview plugin: http://code.google.com/p/jquery-scrollview/ I have tried adding a few lines to the plugin to store variables of scrollTop and Left and then replacing two hidden input values with x and y in my page. And then on the returned ajax html in the div I am trying to on a button click (for example) retrieve the values of the two hidden inputs.... Heres what i added to the plugin (i'm no js expert!): .mouseout(function(){ var _m = this.m; var lasty = _m.scrollTop(); getElementById("ycord").value = lasty; var lastx = _m.scrollLeft(); getElementById("xcord").value = lastx; self.stopgrab(); }) Still no luck!! How can I get the scrollTop and scrollLeft and successfully prepare them for sending onto another php script!? Thanks:) stefpretty

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• Is there "good" PRNG generating values without hidden state?

  - by actual

  I need some good pseudo random number generator that can be computed like a pure function from its previous output without any state hiding. Under "good" I mean: I must be able to parametrize generator in such way that running it for 2^n iterations with any parameters should cover all or almost all values between 0 and 2^n - 1, where n is the number of bits in output value. Combined generator output of n + p bits must cover all or almost all values between 0 and 2^(n + p) - 1 if I run it for 2^n iterations for every possible combination of its parameters, where p is the number of bits in parameters. For example, LCG can be computed like a pure function and it can meet first condition, but it can not meet second one. Say, we have 32-bit generator, m = 2^32 and it is constant, our p = 64 (two 32-bit parameters a and c), n + p = 96, so we must peek data by three ints from output to meet second condition. Unfortunately, condition can not be meet because of strictly alternating sequence of odd and even ints in output. To overcome this, hidden state must be introduced, but that makes function not pure and breaks first condition (period become much longer). Am I wanting too much?

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• Randomly and uniquely iterating over a range

  - by Synetech

  Say you have a range of values (or anything else) and you want to iterate over the range and stop at some indeterminate point. Because the stopping value could be anywhere in the range, iterating sequentially is no good because it causes the early values to be accessed more often than later values (which is bad for things that wear out), and also because it reduces performance since it must traverse extra values. Randomly iterating is better because it will (on average) increase the hit-rate so that fewer values have to be accessed before finding the right one, and also distribute the accesses more evenly (again, on average). The problem is that the standard method of randomly jumping around will result in values being accessed multiple times, and has no automatic way of determining when each value has been checked and thus the whole range has been exhausted. One simplified and contrived solution could be to make a list of each value, pick one at random, then remove it. Each time through the loop, you pick one fromt he set of remaining items. Unfortunately this only works for small lists. As a (forced) example, say you are creating a game where the program tries to guess what number you picked and shows how many guess it took. The range is between 0-255 and instead of asking Is it 0? Is it 1? Is it 2?…, you have it guess randomly. You could create a list of 255 numbers, pick randomly and remove it. But what if the range was between 0-232? You can’t really create a 4-billion item list. I’ve seen a couple of implementations RNGs that are supposed to provide a uniform distribution, but none that area also supposed to be unique, i.e., no repeated values. So is there a practical way to randomly, and uniquely iterate over a range?

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• Algorithm to pick values from set to match target value?

  - by CSharperWithJava

  I have a fixed array of constant integer values about 300 items long (Set A). The goal of the algorithm is to pick two numbers (X and Y) from this array that fit several criteria based on input R. Formal requirement: Pick values X and Y from set A such that the expression X*Y/(X+Y) is as close as possible to R. That's all there is to it. I need a simple algorithm that will do that. Additional info: The Set A can be ordered or stored in any way, it will be hard coded eventually. Also, with a little bit of math, it can be shown that the best Y for a given X is the closest value in Set A to the expression X*R/(X-R). Also, X and Y will always be greater than R From this, I get a simple iterative algorithm that works ok: int minX = 100000000; int minY = 100000000; foreach X in A if(X<=R) continue; else Y=X*R/(X-R) Y=FindNearestIn(A, Y);//do search to find closest useable Y value in A if( X*Y/(X+Y) < minX*minY/(minX+minY) ) then minX = X; minY = Y; end end end I'm looking for a slightly more elegant approach than this brute force method. Suggestions?

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• How can I make an prototype ajax request with an array of values as a parameter?

  - by andresbravog

  i'm trying to make a ajax update in prototype with some values from a multirecordselect that sends a requests like. Parameters: {"action"=>"use_campaign", "campaigns"=> ["27929","27932"] , "advertiser_id"=>"", "controller"=>"admin/reporting", "ad_id"=>""} as you can see the request sends the "campaigns" elements as an array of values, i'm trying to do the same with this js code over prototype 7. // get the campaigns var campaign_ids = {}; var campaigns = $('filter_form').getInputs("hidden","report[campaigns][]"); campaigns.each( function(field) { campaign_ids.push(field.value); }); new Ajax.Updater('ad_filter', '/admin/reporting/use_campaign', { method : 'get', asynchronous : true, evalScripts : true, parameters : { 'advertiser_id' : $('filter_form')['report[advertiser_id]'].value, 'ad_id' : $('filter_form')['report[ad_id]'].value, 'campaigns' : campaign_ids } }); the campaigns_ids is getting the correct info as an array like: [ "27929", "27932" ] but seems that prototype ajax update is sending a request like: http://my_domain/admin/reporting/use_campaign?ad_id=&advertiser_id=&campaigns=27929&campaigns=27932 what sends parameters like: Parameters: {"action"=>"use_campaign", "campaigns"=> "27929" , "advertiser_id"=>"", "controller"=>"admin/reporting", "ad_id"=>""} I also tryed with Object.toJSON(campaign_ids) but i only get an escaped string like Parameters: {"action"=>"use_campaign", "campaigns"=>"[\"27929\",\"27932\"]" , "advertiser_id"=>"", "controller"=>"admin/reporting", "ad_id"=>""} There is anyway to do this as I wish? Thanks for all.

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• Accessing a struct collection property from within another collection

  - by paddyb

  I have a struct that I need to store in a collection. The struct has a property that returns a Dictionary. public struct Item { private IDictionary<string, string> values; public IDictionary<string, string> Values { get { return this.values ?? (this.values = new Dictionary<string, string>()); } } } public class ItemCollection : Collection<Item> {} When testing I've found that if I add the item to the collection and then try to access the dictionary the structs values property is never updated. var collection = new ItemCollection { new Item() }; // pre-loaded with an item collection[0].Values.Add("myKey", "myValue"); Trace.WriteLine(collection[0].Values["myKey"]); // KeyNotFoundException here However if I load up the item first and then add it to a collection the values field is maintained. var collection = new ItemCollection(); var item = new Item(); item.Values.Add("myKey", "myValue"); collection.Add(item); Trace.WriteLine(collection[0].Values["myKey"]); // ok I've already decided that a struct is the wrong option for this type, and when using a class the issue doesn't occur, but I'm curious what's different between the two methods. Can anybody explain what's happening?

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• How to take a collection of bytes and pull typed values out of it?

  - by Pat

  Say I have a collection of bytes var bytes = new byte[] {0, 1, 2, 3, 4, 5, 6, 7}; and I want to pull out a defined value from the bytes as a managed type, e.g. a ushort. What is a simple way to define what types reside at what location in the collection and pull out those values? One (ugly) way is to use System.BitConverter and a Queue or byte[] with an index and simply iterate through, e.g.: int index = 0; ushort first = System.BitConverter.ToUint16(bytes, index); index += 2; // size of a ushort int second = System.BitConverter.ToInt32(bytes, index); index += 4; ... This method gets very, very tedious when you deal with a lot of these structures! I know that there is the System.Runtime.InteropServices.StructLayoutAttribute which allows me to define the locations of types inside a struct or class, but there doesn't seem to be a way to import the collection of bytes into that struct. If I could somehow overlay the struct on the collection of bytes and pull out the values, that would be ideal. E.g. Foo foo = (Foo)bytes; // doesn't work because I'd need to implement the implicit operator ushort first = foo.first; int second = foo.second; ... [StructLayout(LayoutKind.Explicit, Size=FOO_SIZE)] public struct Foo { [FieldOffset(0)] public ushort first; [FieldOffset(2)] public int second; } Any thoughts on how to achieve this?

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