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  • How to insert records in master/detail relationship

    - by croceldon
    I have two tables: OutputPackages (master) |PackageID| OutputItems (detail) |ItemID|PackageID| OutputItems has an index called 'idxPackage' set on the PackageID column. ItemID is set to auto increment. Here's the code I'm using to insert masters/details into these tables: //fill packages table for i := 1 to 10 do begin Package := TfPackage(dlgSummary.fcPackageForms.Forms[i]); if Package.PackageLoaded then begin with tblOutputPackages do begin Insert; FieldByName('PackageID').AsInteger := Package.ourNum; FieldByName('Description').AsString := Package.Title; FieldByName('Total').AsCurrency := Package.Total; Post; end; //fill items table for ii := 1 to 10 do begin Item := TfPackagedItemEdit(Package.fc.Forms[ii]); if Item.Activated then begin with tblOutputItems do begin Append; FieldByName('PackageID').AsInteger := Package.ourNum; FieldByName('Description').AsString := Item.Description; FieldByName('Comment').AsString := Item.Comment; FieldByName('Price').AsCurrency := Item.Price; Post; //this causes the primary key exception end; end; end; end; This works fine as long as I don't mess with the MasterSource/MasterFields properties in the IDE. But once I set it, and run this code I get an error that says I've got a duplicate primary key 'ItemID'. I'm not sure what's going on - this is my first foray into master/detail, so something may be setup wrong. I'm using ComponentAce's Absolute Database for this project. How can I get this to insert properly? Update Ok, I removed the primary key restraint in my db, and I see that for some reason, the autoincrement feature of the OutputItems table isn't working like I expected. Here's how the OutputItems table looks after running the above code: ItemID|PackageID| 1 |1 | 1 |1 | 2 |2 | 2 |2 | I still don't see why all the ItemID values aren't unique.... Any ideas?

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  • JqGrid updating grid on add

    - by CSharpAtl
    Scenario: I have three columns in my grid but only one is editable, the other two are filled in on the server side. I am using the built in add functionality of jqGrid and NOT refreshing the grid on successfully add. I would like to have the row added to the grid, like it does automatically, but would like to add it myself because it only adds the one column that is marked 'editable'. I cannot seem to find a way to block the row from being automatically added to the grid, or a way to override the built in add functionality in the grid. My idea was to add the row myself because I will have received back the full row of data back on my submit. Questions: Is there a way to stop the grid from automatically adding the row when I do not want a grid refresh, so that I can manually add all the data for the row? Is it possible to use the built in add button and override the onClick, without digging and and directly figuring out what jqGrid calls the button? Any better ideas on how to accomplish getting the row added to the grid from the server side without doing it all manually...ie. create my own add button, and popup a dialog and handle all the submit functionality? EDIT What would help is if I could stop the grid from auto adding the row...I can deal with doing it myself.

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  • mysql and trigger usage question

    - by dhruvbird
    I have a situation in which I don't want inserts to take place (the transaction should rollback) if a certain condition is met. I could write this logic in the application code, but say for some reason, it has to be written in MySQL itself (say clients written in different languages will be inserting into this MySQL InnoDB table) [that's a separate discussion]. Table definition: CREATE TABLE table1(x int NOT NULL); The trigger looks something like this: CREATE TRIGGER t1 BEFORE INSERT ON table1 FOR EACH ROW IF (condition) THEN NEW.x = NULL; END IF; END; I am guessing it could also be written as(untested): CREATE TRIGGER t1 BEFORE INSERT ON table1 FOR EACH ROW IF (condition) THEN ROLLBACK; END IF; END; But, this doesn't work: CREATE TRIGGER t1 BEFORE INSERT ON table1 ROLLBACK; You are guaranteed that: Your DB will always be MySQL Table type will always be InnoDB That NOT NULL column will always stay the way it is Question: Do you see anything objectionable in the 1st method?

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  • Binding a Button to a GridView

    - by Tyler
    This a pretty simple question, I'm just not sure how to do it exactly. I would like to bind a Button or perhaps ImageButton to a GridView in ASP.NET/C#. Currently, the GridView has two columns and is bound to a DataTable with two columns. I want to add a third column to the GridView, which will include the Button. I know GridView has ButtonField, but I'm not too sure how to go about using it to do what I want. I want to dynamically generate these Buttons and add them to the GridView. Here is how my GridView looks right now: <asp:GridView ID="GridView1" Runat="server"> <Columns> <asp:HyperLinkField HeaderText="Display Name" DataNavigateUrlFields="DISPNAME" DataNavigateUrlFormatString="ViewItem.aspx" DataTextField="DISPNAME"> <ItemStyle Width="70%" /> </asp:HyperLinkField> <asp:BoundField DataField="TypeDisp" HeaderText="Type"> <ItemStyle Width="20%" /> </asp:BoundField> </Columns> </asp:GridView>

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  • Vertically Merge Multiple Tables in MySQL by Joint Primary Key

    - by world
    Hello, I'll attempt to make my question as clear as possible. I'm fairly unexperienced with SQL, only know the really basic queries. In order to have a better idea I'd been reading the MySQL manual for the past few days, but I couldn't really find a concrete solution and my needs are quite specific. I've got 3 MySQL MyISAM tables: table1, table2 and table3. Each table has an ID column (ID, ID2, ID3 respectively), and different data columns. For example table1 has [ID, Name, Birthday, Status, ...] columns, table2 has [ID2, Country, Zip, ...], table3 has [ID3, Source, Phone, ...] you get the idea. The ID, ID2, ID3 columns are common to all three tables... if there's an ID value in table1 it will also appear in table2 and table3. The number of rows in these tables is identical, about 10m rows in each table. What I'd like to do is create a new table that contains (most of) the columns of all three tables and merge them into it. The dates, for instance, must be converted because right now they're in VARCHAR YYYYMMDD format. Reading the MySQL manual I figured STR_TO_DATE() would do the job, but I don't know how to write the query itself in the first place so I have no idea how to integrate the date conversion. So basically, after I create the new table (which I do know how to do), how can I merge the three tables into it, integrating into the query the date conversion?

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  • Best strategy for synching data in iPhone app

    - by iamj4de
    I am working on a regular iPhone app which pulls data from a server (XML, JSON, etc...), and I'm wondering what is the best way to implement synching data. Criteria are speed (less network data exchange), robustness (data recovery in case update fails), offline access and flexibility (adaptable when the structure of the database changes slightly, like a new column). I know it varies from app to app, but can you guys share some of your strategy/experience? For me, I'm thinking of something like this: 1) Store Last Modified Date in iPhone 2) Upon launching, send a message like getNewData.php?lastModifiedDate=... 3) Server will process and send back only modified data from last time. 4) This data is formatted as so: <+><data id="..."></data></+> // add this to SQLite/CoreData <-><data id="..."></data></-> // remove this <%><data id="..."><attribute>newValue</attribute></data></%> // new modified value I don't want to make <+, <-, <%... for each attribute as well, because it would be too complicated, so probably when receive a <% field, I would just remove the data with the specified id and then add it again (assuming id here is not some automatically auto-incremented field). 5) Once everything is downloaded and updated, I will update the Last Modified Date field. The main problem with this strategy is: If the network goes down when I am updating something = the Last Modified Date is not yet updated = next time I relaunch the app, I will have to go through the same thing again. Not to mention potential inconsistent data. If I use a temporary table for update and make the whole thing atomic, it would work, but then again, if the update is too long (lots of data change), the user has to wait a long time until new data is available. Should I use Last-Modified-Date for each of the data field and update data gradually?

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  • writing into csv file

    - by arin
    I recived alarms in a form of text as the following NE=JKHGDUWJ3 Alarm=Data Center STALZ AC Failure Occurrence=2012/4/3 22:18:19 GMT+02:00 Clearance=Details=Cabinet No.=0, Subrack No.=40, Slot No.=0, Port No.=5, Board Type=EDS, Site No.=49, Site Type=HSJYG500 GSM, Site Name=Google1 . I need to fill it in csv file so later I can perform some analysis I came up with this namespace AlarmSaver { public partial class Form1 : Form { string filesName = "c:\\alarms.csv"; public Form1() { InitializeComponent(); } private void buttonSave_Click(object sender, EventArgs e) { if (!File.Exists(filesName)) { string header = "NE,Alarm,Occurrence,Clearance,Details"; File.AppendAllText(filesName,header+Environment.NewLine); } StringBuilder sb = new StringBuilder(); string line = textBoxAlarm.Text; int index = line.IndexOf(" "); while (index > 0) { string token = line.Substring(0, index).Trim(); line = line.Remove(0, index + 2); string[] values = token.Split('='); if (values.Length ==2) { sb.Append(values[1] + ","); } else { if (values.Length % 2 == 0) { string v = token.Remove(0, values[0].Length + 1).Replace(',', ';'); sb.Append(v + ","); } else { sb.Append("********" + ","); string v = token.Remove(0, values[0].Length + 1 + values[1].Length + 1).Replace(',', ';'); sb.Append(v + ","); } } index = line.IndexOf(" "); } File.AppendAllText(filesName, sb.ToString() + Environment.NewLine); } } } the results are as I want except when I reach the part of Details=Cabinet No.=0, Subrack No.=40, Slot No.=0, Port No.=5, Board Type=KDL, Site No.=49, Site Type=JDKJH99 GSM, Site Name=Google1 . I couldnt split them into seperate fields. as the results showing is as I want to split the details I want each element in details to be in a column to be somthin like its realy annoying :-) please help , thank you in advance

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  • Solving Naked Triples in Sudoku

    - by Kave
    Hello, I wished I paid more attention to the math classes back in Uni. :) How do I implement this math formula for naked triples? Naked Triples Take three cells C = {c1, c2, c3} that share a unit U. Take three numbers N = {n1, n2, n3}. If each cell in C has as its candidates ci ? N then we can remove all ni ? N from the other cells in U.** I have a method that takes a Unit (e.g. a Box, a row or a column) as parameter. The unit contains 9 cells, therefore I need to compare all combinations of 3 cells at a time that from the box, perhaps put them into a stack or collection for further calculation. Next step would be taking these 3-cell-combinations one by one and compare their candidates against 3 numbers. Again these 3 numbers can be any possible combination from 1 to 9. Thats all I need. But how would I do that? How many combinations would I get? Do I get 3 x 9 = 27 combinations for cells and then the same for numbers (N)? How would you solve this in classic C# loops? No Lambda expression please I am already confused enough :) Many Thanks for any help,

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  • What is the most efficient/elegant way to parse a flat table into a tree?

    - by Tomalak
    Assume you have a flat table that stores an ordered tree hierarchy: Id Name ParentId Order 1 'Node 1' 0 10 2 'Node 1.1' 1 10 3 'Node 2' 0 20 4 'Node 1.1.1' 2 10 5 'Node 2.1' 3 10 6 'Node 1.2' 1 20 What minimalistic approach would you use to output that to HTML (or text, for that matter) as a correctly ordered, correctly intended tree? Assume further you only have basic data structures (arrays and hashmaps), no fancy objects with parent/children references, no ORM, no framework, just your two hands. The table is represented as a result set, which can be accessed randomly. Pseudo code or plain English is okay, this is purely a conceptional question. Bonus question: Is there a fundamentally better way to store a tree structure like this in a RDBMS? EDITS AND ADDITIONS To answer one commenter's (Mark Bessey's) question: A root node is not necessary, because it is never going to be displayed anyway. ParentId = 0 is the convention to express "these are top level". The Order column defines how nodes with the same parent are going to be sorted. The "result set" I spoke of can be pictured as an array of hashmaps (to stay in that terminology). For my example was meant to be already there. Some answers go the extra mile and construct it first, but thats okay. The tree can be arbitrarily deep. Each node can have N children. I did not exactly have a "millions of entries" tree in mind, though. Don't mistake my choice of node naming ('Node 1.1.1') for something to rely on. The nodes could equally well be called 'Frank' or 'Bob', no naming structure is implied, this was merely to make it readable. I have posted my own solution so you guys can pull it to pieces.

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  • Avoiding secondary selects or joins with Hibernate Criteria or HQL query

    - by Ben Benson
    I am having trouble optimizing Hibernate queries to avoid performing joins or secondary selects. When a Hibernate query is performed (criteria or hql), such as the following: return getSession().createQuery(("from GiftCard as card where card.recipientNotificationRequested=1").list(); ... and the where clause examines properties that do not require any joins with other tables... but Hibernate still performs a full join with other tables (or secondary selects depending on how I set the fetchMode). The object in question (GiftCard) has a couple ManyToOne associations that I would prefer to be lazily loaded in this case (but not necessarily all cases). I want a solution that I can control what is lazily loaded when I perform the query. Here's what the GiftCard Entity looks like: @Entity @Table(name = "giftCards") public class GiftCard implements Serializable { private static final long serialVersionUID = 1L; private String id_; private User buyer_; private boolean isRecipientNotificationRequested_; @Id public String getId() { return this.id_; } public void setId(String id) { this.id_ = id; } @ManyToOne @JoinColumn(name = "buyerUserId") @NotFound(action = NotFoundAction.IGNORE) public User getBuyer() { return this.buyer_; } public void setBuyer(User buyer) { this.buyer_ = buyer; } @Column(name="isRecipientNotificationRequested", nullable=false, columnDefinition="tinyint") public boolean isRecipientNotificationRequested() { return this.isRecipientNotificationRequested_; } public void setRecipientNotificationRequested(boolean isRecipientNotificationRequested) { this.isRecipientNotificationRequested_ = isRecipientNotificationRequested; } }

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  • WPF Notify changes on object

    - by Erik Z
    I have a gridview were I define some columns, like this... <GridViewColumn.CellTemplate> <DataTemplate> <TextBlock Text="{Binding MyProp}" /> </DataTemplate> </GridViewColumn.CellTemplate> I bind my gridview to a collection and implemts INotifyPropertyChanged in the property MyProp. This works well and any changes of MyProp are reflected to the gridview. If I add another column that is bound to the object itself I dont get any notifications/updates. My code... <GridViewColumn.CellTemplate> <DataTemplate> <TextBlock Text="{Binding Converter={StaticResource myConverter}}"/> </DataTemplate> </GridViewColumn.CellTemplate> I think I need something like INotifyPropertyChanged for the object but I have no idea how to do this. Any suggestions?

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  • Why does stored procedure invalidate SQL Cache Dependency?

    - by Fabio Milheiro
    After many hours, I finally realize that I am working correctly with the Cache object in my ASP.NET application but my stored procedures stops it from working correctly. This stored procedure works correctly: CREATE PROCEDURE [dbo].[ListLanguages] @Page INT = 1, @ItemsPerPage INT = 10, @OrderBy NVARCHAR (100) = 'ID', @OrderDirection NVARCHAR(4) = 'DESC' AS BEGIN SELECT ID, [Name], Flag, IsDefault FROM dbo.Languages END But this (the one I wanted) doesn't: CREATE PROCEDURE [dbo].[ListLanguages] @Page INT = 1, @ItemsPerPage INT = 10, @OrderBy NVARCHAR (100) = 'ID', @OrderDirection NVARCHAR(4) = 'DESC', @TotalRecords INT OUTPUT AS BEGIN SET @TotalRecords = 10 EXEC('SELECT ID, Name, Flag, IsDefault FROM ( SELECT ROW_NUMBER() OVER (ORDER BY ' + @OrderBy + ' ' + @OrderDirection + ') as Row, ID, Name, Flag, IsDefault FROM dbo.Languages) results WHERE Row BETWEEN ((' + @Page + '-1)*' + @ItemsPerPage + '+1) AND (' + @Page + '*' + @ItemsPerPage + ')') END I gave the @TotalRecords parameter the value 10 so you can be sure that the problem is not from the COUNT(*) function which I know is not supported well. Also, when I run it from SQL Server Management Studio, it does exactly what it should do. In the ASP.NET application the results are retrieved correctly, only the cache is somehow unable to work! Can you please help? Maybe a hint I believe that the reason why the dependency HasChanged property is related to the fact that the column Row generated from the ROW_NUMBER is only temporary and, therefore, the SQL SERVER is not able to to say whether the results are changed or not. That's why HasChanged is always set to true. Does anyone know how to paginate results from SQL SERVER without using COUNT or ROW_NUMBER functions?

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  • Enum and Dictionary<Enum, Action>

    - by Selcuk
    I hope I can explain my problem in a way that it's clear for everyone. We need your suggestions on this. We have an Enum Type which has more than 15 constants defined. We receive a report from a web service and translate its one column into this Enum type. And based on what we receive from that web service, we run specific functions using Dictionary Why am I asking for ideas? Let's say 3 of these Enum contants meet specific functions in our Dictionary but the rest use the same function. So, is there a way to add them into our Dictionary in a better way rather than adding them one by one? I also want to keep this structure because when it's time, we might have specific functions in the future for the ones that I described as "the rest". To be more clear here's an example what we're trying to do: Enum: public enum Reason{ ReasonA, ReasonB, ReasonC, ReasonD, ReasonE, ReasonF, ReasonG, ReasonH, ReasonI, ReasonJ, ReasonK } Defining our Dictionary: public Dictionary<Reason, Action<CustomClassObj, string>> ReasonHandlers = new Dictionary<Reason, Action<CustomClassObj, string>>{ { Reason.ReasonA, HandleReasonA }, { Reason.ReasonB, HandleReasonB }, { Reason.ReasonC, HandleReasonC }, { Reason.ReasonD, HandleReasonGeneral }, { Reason.ReasonE, HandleReasonGeneral }, { Reason.ReasonF, HandleReasonGeneral }, { Reason.ReasonG, HandleReasonGeneral }, { Reason.ReasonH, HandleReasonGeneral }, { Reason.ReasonI, HandleReasonGeneral }, { Reason.ReasonJ, HandleReasonGeneral }, { Reason.ReasonK, HandleReasonGeneral } }; So basically what I'm asking is, is there a way to add Reason, Function pair more intelligently? Because as you can see after ReasonC, all other reasons use the same function. Thank you for your suggestions.

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  • Is ADO.NET Entity framework database schema update possible ?

    - by fyasar
    Hi All I'm working on proof of concept application like crm and i need your some advice. My application's data layer completely dynamic and run onto EF 3.5. When the user update the entity, change relation or add new column to the database, first i'm planning make for these with custom classes. After I rebuild my database model layer with new changes during the application runtime. And my model layer tie with tightly coupled to my project for easy reflecting model layer changes (It connected to my project via interfaces and loading onto to application domain in the runtime). I need to create dynamic entities, create entity relations and modify them during the runtime after that i need to create change database script for updating database schema. I know ADO.NET team says "we will be able to provide this property in EF 4.0", but i don't need to wait for them. How can i update database changes during the runtime via EF 3.5 ? For example, i need to create new entity or need to change some entity schema, add new properties or change property types after than how can apply these changes on the physical database schema ? Any ideas ?

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  • Variable amount of columns returned in mysqli prepared statement

    - by manyxcxi
    I have a situation where a dynamic query is being generated that could select anywhere from 1 to over 300 different columns across multiple tables. It currently works fine just doing a query, however the issue I'm running into in using a prepared statement is that I do not know how to handle the fact that I don't know how many columns I will be asking for each time and therefor don't know how to process the results. The reason I believe a bind statement will help is because once this query is run once, it will most likely (though not always) be run again with the exact same parameters. Currently I have something like this: $rows = array(); $this->statement = $this->db->prepare($query); $this->statement->bind_param('i',$id); $this->statement->execute(); $this->statement->bind_result($result); while($this->statement->fetch()) { $rows[] = $result; } I know this doesn't work as I want it to, my question is how do I get the data back out of the query. Is it possible to bring the columns back in an associative array by column name, like a standard mysqli query?

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  • Why does one of these statements compile in Scala but not the other?

    - by Jeff
    (Note: I'm using Scala 2.7.7 here, not 2.8). I'm doing something pretty simple -- creating a map based on the values in a simple, 2-column CSV file -- and I've completed it easily enough, but I'm perplexed at why my first attempt didn't compile. Here's the code: // Returns Iterator[String] private def getLines = Source.fromFile(csvFilePath).getLines // This doesn't compile: def mapping: Map[String,String] = { Map(getLines map { line: String => val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() }.toList:_*) } // This DOES compile def mapping: Map[String,String] = { def strPair(line: String): (String,String) = { val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() } Map(getLines.map( strPair(_) ).toList:_*) } The compiler error is CsvReader.scala:16: error: value toList is not a member of (St ring) = (java.lang.String, java.lang.String) [scalac] possible cause: maybe a semicolon is missing before `value toList'? [scalac] }.toList:_*) [scalac] ^ [scalac] one error found So what gives? They seem like they should be equivalent to me, apart from the explicit function definition (vs. anonymous in the nonworking example) and () vs. {}. If I replace the curly braces with parentheses in the nonworking example, the error is "';' expected, but 'val' found." But if I remove the local variable definition and split the string twice AND use parens instead of curly braces, it compiles. Can someone explain this difference to me, preferably with a link to Scala docs explaining the difference between parens and curly braces when used to surround method arguments?

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  • Discriminator based on joined property

    - by Andrew
    Suppose I have this relationship: abstract class Base { int Id; int JoinedId; ... } class Joined { int Id; int Discriminator; ... } class Sub1 : Base { ... } class Sub2 : Base { ... } for the following tables: table Base ( Id int, JoinedId int, ... ) table Joined ( Id int, Discriminator int, ... ) I would like to set up a table-per-hierarchy inheritance mapping for the Base, Sub1, Sub2 relationships, but using the Disciminator property from the Joined class as the discriminator. Here's the general idea for the mapping file: <class name="Base" table="Base"> <id name="Id"><generator class="identity"/></id> <discriminator /> <!-- ??? or <join> or <many-to-one>? --> <subclass name="Sub1" discriminator-value="1">...</subclass> <subclass name="Sub2" discriminator-value="2">...</subclass> </class> Is there any way of accomplishing something like this with the <discriminator>, <join>, or <many-to-one>? NHiberante seems to assume the discriminator is a column on the given table (which makes sense to me.. I know this is unorthodox). Thanks.

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  • Nhibernate fires SQL commands

    - by Chris
    Hi all, when updating an entity A, NHibernate also send an SQL update command for some other entity B. A and B are not related. Just before saving entity A, the parent of entity B is loaded via a SQLQuery. Then, when accessed, B is lazy loaded (part of a collection). If I save entity A an update statement for entity B is generated as well. How can that be, that when saving an entity, another entity loaded before but is not related to the entity saved, is updated as well?! Can I somehow track where the update comes from? Btw. I am using an save event listener. Could it be that this is always triggered for entity loaded, even though they are not saved explicitly? public class EntitySaveEventListener : NHibernate.Event.Default.DefaultSaveEventListener { protected override object PerformSaveOrUpdate(SaveOrUpdateEvent e) { //auditing return base.PerformSaveOrUpdate(e); } } Update (sorry for providing not enough info): I tracked it down a bit. A select stateement on a entity called address is executed (is it lazy loaded by a parent). Then I create a new entity called Request. Right before saving this entity a session flush is called which updates the address, even though I did not call save or update on the address. Address is a collection within Request. <class name="Request" table="Request"> <bag name="addresses" access="field" cascade="all-delete-orphan" where="IsDeleted = 0"> <key column="RequestId"/> <one-to-many class="Address"/> </bag> ... // address is fetched only NHibernate.SQL: 2010-02-17 11:47:21,306 [21] DEBUG NHibernate.SQL [(null)] - SELECT addresses0_.RequestId as ServiceP8_3_, .... // session flushed here // address is updated NHibernate.SQL: 2010-02-17 11:47:34,306 [21] DEBUG NHibernate.SQL [(null)] - Batch commands: command 0:UPDATE Address SET Street = @p0, ..... Would the address be updated automatically when it is manipulated somehow even though it is not explicitly saved via it's parent (cascade)?

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  • Fastest way to convert a list of doubles to a unique list of integers?

    - by javanix
    I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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  • SQL, MVC, Entity Framework

    - by Anthony
    Hi Im using the above technologies and have ran into what I presume is a design issue I have made. I have an Artwork table in my DB and have been able to add art (I now think of these as Digital Products) to a shopping cart + CartLine table fine. The system I have that adds art to galleries and user accounts etc works fine. Now the client wants to sell T-shirts, Mugs and Pens etc, 'HardwareProducts' so I have created a 'HardwareProducts' table. Now I have two different product types in two tables. I use GUID's as the PK's in both the HardwareProducts table and Artwork table. When a customer adds an item to their cart I store the GUID in the ProductID column in the CartItems table. The issue is the database will not know which table to reference when I bring the LineItem object up through my ORM to the front end. In OOP I can see how you would have a base class of Product, and then a DigitalProduct class and HardwareProduct class drived from it, but how do you model this in SQL Server and the Entity Framework please, or is there another way?

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  • Understanding sql queries formulation methodoloy. How do you think while formulating Sql Queries

    - by Shantanu Gupta
    I have been working on sql server and front end coding and have usually faced problem formulating queries. I do understand most of the concepts of sql that are needed in formulating queries but whenever some new functionality comes into the picture that can be dont using sql query, i do usually fails resolving them. I am very comfortable with select queries using joins and all such things but when it comes to DML operation i usually fails For every query that i never done before I usually finds uncomfortable with that while creating them. Whenever I goes for an interview I usually faces this problem. Is it their some concept behind approaching on formulating sql queries. Eg. I need to create an sql query such that A table contain single column having duplicate record. I need to remove duplicate records. I know i can find the solution to this query very easily on Googling, but I want to know how everyone comes to the desired result. Is it something like Practice Makes Man Perfect i.e. once you did it, next time you will be able to formulate or their is some logic or concept behind.

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  • Understanding MongoDB(and NoSQL in general) and How to make the best use of it

    - by Earlz
    Hello, I am beginning to think that my next project I am wanting to do would work better with a NoSQL solution. The project would either involve a ton of 2-column tables or a ton of dynamic queries with dynamically generated columns in a traditional SQL database. So I feel a NoSQL database would be much cleaner. I'm looking at MongoDB and it looks pretty promising. Anyway, I'm attempting to make sense of it all. Also, I will be using MongoMapper in Ruby. Anyway though, I'm confused as to how to layout things in such a freeform database. I've read http://stackoverflow.com/questions/2170152/nosql-best-practices and the answer there says that normalization is usually bad in a NoSQL DB. So how would be the best way of laying out say a simple blog with users, posts, and comments? My natural thought was to have 3 collections for each and then link them by a unique ID. But this apparently is wrong? So, what are some of the ways to lay out such a thing? My concern with the answer given in the other question is what if the author's name changed. You'd have to go through updating a ton of posts and comments. But is this an ok thing to do with NoSQL?

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  • Rails running multiple delayed_job - lock tables

    - by pepernik
    Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

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  • Concatenate CLOB-rows with PL/SQL

    - by david K
    Hi, I've got a table which has an id and a clob content like: Create Table v_example_l ( nip number, xmlcontent clob ); We insert our data: Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>delta</name><content>548484646846484</content></block></section>'); Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>omega</name><content>545648468484</content></block></section>'); Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>gamma</name><content>54564846qsdqsdqsdqsd8484</content></block></section>'); I'm trying to do a function that concatenates the rows of the clob that gone be the result of a select, i mean without having to give multiple parameter about the name of table or such, i should only give here the column that contain the clobs, and it should handle the rest. CREATE OR REPLACE function assemble_clob(q varchar2) return clob is v_clob clob; tmp_lob clob; hold VARCHAR2(4000); --cursor c2 is select xmlcontent from V_EXAMPLE_L where id=17852 cur sys_refcursor; begin OPEN cur FOR q; LOOP FETCH cur INTO tmp_lob; EXIT WHEN cur%NOTFOUND; --v_clob := v_clob || XMLTYPE.getClobVal(tmp_lob.xmlcontent); v_clob := v_clob || tmp_lob; END LOOP; return (v_clob); --return (dbms_xmlquery.getXml( dbms_xmlquery.set_context("Select 1 from dual")) ) end assemble_clob; The function is broken... (if anybody could give me a help, thanks a lot, and i'm noob in sql so ....). Thanks!

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  • Fastest way to modify a decimal-keyed table in MySQL?

    - by javanix
    I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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