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• WPF Empty Row in ItemsControl Binding with ObservableCollection

  - by YoMo

  I have ItemsControl Binding with ObservableCollection, every think is oky excipt when ObservableCollection was empty the ItemsControl showing one empty row !! <ItemsControl Visibility="Visible" ItemsSource="{Binding ocItemsinInvoice,Mode=TwoWay}" x:Name="test" Margin="10,-32,0,207" Width="412" HorizontalAlignment="Left"> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <UniformGrid Columns="1" VerticalAlignment="Top" /> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> <ItemsControl.ItemTemplate> <DataTemplate> <Button x:Name="btnOpenInvoice" Style="{StaticResource OpenInvoicesButton}" FontSize="12" Width="300" Height="60" Foreground="#ff252526"> <StackPanel Orientation="Vertical"> <TextBlock Text="{Binding Item.ItemName}" HorizontalAlignment="Center" VerticalAlignment="Center" /> </StackPanel> </Button> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> How can I remove it?

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• Using Python to get a CSV output for the following example.

  - by Az

  Hi there, I'm back again with my ongoing saga of Student-Project Allocation questions. Thanks to Moron (who does not match his namesake) I've got a bit of direction for an evaluation portion of my project. Going with the idea of the Assignment Problem and Hungarian Algorithm I would like to express my data in the form of a .csv file which would end up looking like this in spreadsheet form. This is based on the structure I saw here. | | Project 1 | Project 2 | Project 3 | |----------|-----------|-----------|-----------| |Student1 | | 2 | 1 | |----------|-----------|-----------|-----------| |Student2 | 1 | 2 | 3 | |----------|-----------|-----------|-----------| |Student3 | 1 | 3 | 2 | |----------|-----------|-----------|-----------| To make it less cryptic: the rows are the Students/Agents and the columns represent Projects/Task. Obviously ONE project can be assigned to ONE student. That, in short, is what my project is about. The fields represent the preference weights the students have placed upon the projects (ranging from 1 to 10). If blank, that student does not want that project and there's no chance of him/her being assigned such. Anyway, my data is stored within dictionaries. Specifically the students and projects dictionaries such that: students[student_id] = Student(student_id, student_name, alloc_proj, alloc_proj_rank, preferences) where preferences is in the form of a dictionary such that preferences[rank] = {project_id} and projects[project_id] = Project(project_id, project_name) I'm aware that sorted(students.keys()) will give me a sorted list of all the student IDs which will populate the row labels and sorted(projects.keys()) will give me the list I need to populate the column labels. Thus for each student, I'd go into their preferences dictionary and match the applicable projects to ranks. I can do that much. Where I'm failing is understanding how to create a .csv file. Any help, pointers or good tutorials will be highly appreciated.

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• Load SQL query result data into cache in advance

  - by Marc

  I have the following situation: .net 3.5 WinForm client app accessing SQL Server 2008 Some queries returning relatively big amount of data are used quite often by a form Users are using local SQL Express and restarting their machines at least daily Other users are working remotely over slow network connections The problem is that after a restart, the first time users open this form the queries are extremely slow and take more or less 15s on a fast machine to execute. Afterwards the same queries take only 3s. Of course this comes from the fact that no data is cached and must be loaded from disk first. My question: Would it be possible to force the loading of the required data in advance into SQL Server cache? Note My first idea was to execute the queries in a background worker when the application starts, so that when the user starts the form the queries will already be cached and execute fast directly. I however don't want to load the result of the queries over to the client as some users are working remotely or have otherwise slow networks. So I thought just executing the queries from a stored procedure and putting the results into temporary tables so that nothing would be returned. Turned out that some of the result sets are using dynamic columns so I couldn't create the corresponding temp tables and thus this isn't a solution. Do you happen to have any other idea?

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• placing pop up based on the mouse position(x,y)RSS Feed

  - by prince23

  hi, right now i am showing pop at the botton of the screen. i need to change them according to the value(x,y) whhere i have moved the mouse here i need to get the MouseEventArgs e postion that is its x:value and y:value based on that i need to place the pop up in the screen i need to get the mouse x, y postion? is it possiable to get its value? private void DG_LoadingRow(object sender, DataGridRowEventArgs e) { DataGridRow row = e.Row; int index = 0; foreach (DataGridColumn colGrid in DG.Columns) { if(colGrid .Header == "ID" || colGrid .Header == "Name") { FrameworkElement cellContent = colGrid .GetCellContent(e.Row); DataGridCell cell = cellContent.Parent as DataGridCell; cell.MouseEnter -= cell_MouseEnter; cell.MouseEnter += new MouseEventHandler(cell_MouseEnter); cell.MouseLeave -= cell_MouseLeave; cell.MouseLeave += new MouseEventHandler(cell_MouseLeave); } } } void cell_MouseLeave(object sender, MouseEventArgs e) { //Hide your popup } void cell_MouseEnter(object sender, MouseEventArgs e) { **// here i need to get the mouse position that is its x,y value based on that i can place my modal pop up in that postion. my pop is defined in xaml page here i will be assigning only its position where i need to place my modal pop up.** //

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• Importing data from third party datasource (open architecture design )

  - by mare

  How would you design an application (classes, interfaces in class library) in .NET when we have a fixed database design on our side and we need to support imports of data from third party data sources, which will most likely be in XML? For instance, let us say we have a Products table in our DB which has columns Id Title Description TaxLevel Price and on the other side we have for instance Products: ProductId ProdTitle Text BasicPrice Quantity. Currently I do it like this: Have the third party XML convert to classes and XSD's and then deserialize its contents into strong typed objects (what we get as a result of this process is classes like ThirdPartyProduct, ThirdPartyClassification, etc.). Then I have methods like this: InsertProduct(ThirdPartyProduct newproduct) I do not use interfaces at the moment but I would like them to. What I would like is implement something like public class Contoso_ProductSynchronization : ProductSynchronization InsertProduct(ContosoProduct p) where ProductSynchronization will be an interface or abstract class. There will most likely be many implementations of ProductSynchronization. I cannot hardcode the types - classes like ContosoProduct, NorthwindProduct might be created from the third party XML's (so preferably I would continue to use deserialization). Hopefully someone will understand what I'm trying to explain here. Just imagine you are the seller and you have numerous providers and each one uses their own proprietary XML format. I don't mind the development, which will of course be needed everytime new format appears, because it will only require 10-20 methods to be implemented, I just want the architecture to be open and support that.

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• PHP: What is an efficient way to parse a text file containing very long lines?

  - by Shaun

  I'm working on a parser in php which is designed to extract MySQL records out of a text file. A particular line might begin with a string corresponding to which table the records (rows) need to be inserted into, followed by the records themselves. The records are delimited by a backslash and the fields (columns) are separated by commas. For the sake of simplicity, let's assume that we have a table representing people in our database, with fields being First Name, Last Name, and Occupation. Thus, one line of the file might be as follows [People] = "\Han,Solo,Smuggler\Luke,Skywalker,Jedi..." Where the ellipses (...) could be additional people. One straightforward approach might be to use fgets() to extract a line from the file, and use preg_match() to extract the table name, records, and fields from that line. However, let's suppose that we have an awful lot of Star Wars characters to track. So many, in fact, that this line ends up being 200,000+ characters/bytes long. In such a case, taking the above approach to extract the database information seems a bit inefficient. You have to first read hundreds of thousands of characters into memory, then read back over those same characters to find regex matches. Is there a way, similar to the Java String next(String pattern) method of the Scanner class constructed using a file, that allows you to match patterns in-line while scanning through the file? The idea is that you don't have to scan through the same text twice (to read it from the file into a string, and then to match patterns) or store the text redundantly in memory (in both the file line string and the matched patterns). Would this even yield a significant increase in performance? It's hard to tell exactly what PHP or Java are doing behind the scenes.

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• Primary key/foreign Key naming convention

  - by Jeremy

  In our dev group we have a raging debate regarding the naming convention for Primary and Foreign Keys. There's basically two schools of thought in our group: 1) Primary Table (Employee) Primary Key is called ID Foreign table (Event) Foreign key is called EmployeeID 2) Primary Table (Employee) Primary Key is called EmployeeID Foreign table (Event) Foreign key is called EmployeeID I prefer not to duplicate the name of the table in any of the columns (So I prefer option 1 above). Conceptually, it is consisted with a lot of the recommended practices in other languages, where you don't use the name of the object in its property names. I think that naming the foreign key EmployeeID (or Employee_ID might be better) tells the reader that it is the ID column of the Employee Table. Some others prefer option 2 where you name the primary key prefixed with the table name so that the column name is the same throughout the database. I see that point, but you now can not visually distinguish a primary key from a foreign key. Also, I think it's redundant to have the table name in the column name, because if you think of the table as an entity and a column as a property or attribute of that entity, you think of it as the ID attribute of the Employee, not the EmployeeID attribute of an employee. I don't go an ask my coworker what his PersonAge or PersonGender is. I ask him what his Age is. So like I said, it's a raging debate and we go on and on and on about it. I'm interested to get some new perspective.

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• R: manipulating data.frames containing strings and booleans.

  - by Mike Dewar

  Hello. I have a data.frame in R; it's called p. Each element in the data.frame is either True or False. My variable p has, say, m rows and n columns. For every row there is strictly only one TRUE element. It also has column names, which are strings. What I would like to do is the following: For every row in p I see a TRUE I would like to replace with the name of the corresponding column I would then like to collapse the data.frame, which now contains FALSEs and column names, to a single vector, which will have m elements. I would like to do this in an R-thonic manner, so as to continue my enlightenment in R and contribute to a world without for-loops. I can do step 1 using the following for loop: for (i in seq(length(colnames(p)))) { p[p[,i]==TRUE,i]=colnames(p)[i] } but theres's no beauty here and I have totally subscribed to this for-loops-in-R-are-probably-wrong mentality. Maybe wrong is too strong but they're certainly not great. I don't really know how to do step 2. I kind of hoped that the sum of a string and FALSE would return the string but it doesn't. I kind of hoped I could use an OR operator of some kind but can't quite figure that out (Python responds to False or 'bob' with 'bob'). Hence, yet again, I appeal to you beautiful Rstats people for help!

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• Cache data in SQL CE database

  - by user93422

  Background I have an SQL CE database, that is constantly updated (every second). I have a (web) application that allows a user to look at the data in real-time. At some point a user can click "take a snapshot" button, and it will open the snapshot in a different window. And then on that form, there is "print" and "download" buttons that will either generate a page for printing, or will stream the data as CSV file - but same data snapshot has to be used, i.e. I can't go to the DB to get latest data for that. Details SQL CE dabatase is exposed through WCF web service. Snapshot consists of up to 500 records, 10 columns each. Expiration time on the snapshot of 2 hours is sufficient. It is a low-traffic application, so I don't expect more than few (5) connections at the same time. Loosing snapshot is not a big deal, user can simply generate new one. database is accessed by self-hosted WCF web service using Linq-to-SQL. Web site is ASP.NET MVC hosted on UltiDev Cassini. database, and web site are most likely be on the same box, when deployed. The entire app is intranet bound. Problem I need to cache the snapshot of the data at the moment user pressed "take a snapshot" button, so that I can use same data to generate print page, or generate a file for download. Solution 1: Each time there is a need to generate a snapshot, I will create a table in the database. Since there are no temp tables in SQL CE, I will need to clean it up myself. Solution 2: Cache the snapshot in-memory on either DB server, or web server. Question: Is there anything wrong with proposed solutions? Any different solution suggestions?

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• How can I free all allocated memory at once?

  - by Tommy

  Here is what I am working with: char* qdat[][NUMTBLCOLS]; char** tdat[]; char* ptr_web_data; // Loop thru each table row of the query result set for(row_index = 0; row_index < number_rows; row_index++) { // Loop thru each column of the query result set and extract the data for(col_index = 0; col_index < number_cols; col_index++) { ptr_web_data = (char*) malloc((strlen(Data) + 1) * sizeof(char)); memcpy (ptr_web_data, column_text, strlen(column_text) + 1); qdat[row_index][web_data_index] = ptr_web_data; } } tdat[row_index] = qdat[col_index]; After the data is used, the memory allocated is released one at a time using free(). for(row_index = 0; row_index < number_rows; row_index++) { // Loop thru all columns used for(col_index = 0; col_index < SARWEBTBLCOLS; col_index++) { // Free memory block pointed to by results set array free(tdat[row_index][col_index]); } } Is there a way to release all the allocated memory at once, for this array? Thank You.

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• Getting unpredictable data into a tabular format

  - by Acorn

  The situation: Each page I scrape has <input> elements with a title= and a value= I don't know what is going to be on the page. I want to have all my collected data in a single table at the end, with a column for each title. So basically, I need each row of data to line up with all the others, and if a row doesn't have a certain element, then it should be blank (but there must be something there to keep the alignment). eg. First page has: {animal: cat, colour: blue, fruit: lemon, day: monday} Second page has: {animal: fish, colour: green, day: saturday} Third page has: {animal: dog, number: 10, colour: yellow, fruit: mango, day: tuesday} Then my resulting table should be: animal | number | colour | fruit | day cat | none | blue | lemon | monday fish | none | green | none | saturday dog | 10 | yellow | mango | tuesday Although it would be good to keep the order of the title value pairs, which I know dictionaries wont do. So basically, I need to generate columns from all the titles (kept in order but somehow merged together) What would be the best way of going about this without knowing all the possible titles and explicitly specifying an order for the values to be put in?

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• Creating a [materialised]view from generic data in Oracle/Mysql

  - by Andrew White

  I have a generic datamodel with 3 tables CREATE TABLE Properties ( propertyId int(11) NOT NULL AUTO_INCREMENT, name varchar(80) NOT NULL ) CREATE TABLE Customers ( customerId int(11) NOT NULL AUTO_INCREMENT, customerName varchar(80) NOT NULL ) CREATE TABLE PropertyValues ( propertyId int(11) NOT NULL, customerId int(11) NOT NULL, value varchar(80) NOT NULL ) INSERT INTO Properties VALUES (1, 'Age'); INSERT INTO Properties VALUES (2, 'Weight'); INSERT INTO Customers VALUES (1, 'Bob'); INSERT INTO Customers VALUES (2, 'Tom'); INSERT INTO PropertyValues VALUES (1, 1, '34'); INSERT INTO PropertyValues VALUES (2, 1, '80KG'); INSERT INTO PropertyValues VALUES (1, 2, '24'); INSERT INTO PropertyValues VALUES (2, 2, '53KG'); What I would like to do is create a view that has as columns all the ROWS in Properties and has as rows the entries in Customers. The column values are populated from PropertyValues. e.g. customerId Age Weight 1 34 80KG 2 24 53KG I'm thinking I need a stored procedure to do this and perhaps a materialised view (the entries in the table "Properties" change rarely). Any tips?

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• Extending URIs with 2 queries (i.e. 'viewauthorbooks.php?authorid=4' AND 'orderby=returndate") Possi

  - by Jess

  I have a link in my system as displayed above; 'viewauthorbooks.php?authorid=4' which works fine and generates a page displaying the books only associated with the particular author. However I am implementing another feature where the user can sort the columns (return date, book name etc) and I am using the ORDER BY SQL clause. I have this also working as required for other pages, which do not already have another query in the URI. But for this particular page there is already a paramter returned in the URL, and I am having difficulty in extending it. When the user clicks on the a table column title I'm getting an error, and the original author ID is being lost!! This is the URI link I am trying to use: <th><a href="viewauthorbooks.php?authorid=<?php echo $row['authorid']?>&orderby=returndate">Return Date</a></th> This is so that the data can be sorted in order of Return Date. When I run this; the author ID gets lost for some reason, also I want to know if I am using correct layout to have 2 parameters run in the address? Thanks.

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• Finding the Column Index for a Specific Value

  - by Btibert3

  Hi All, I am having a brain cramp. Below is a toy dataset: df <- data.frame( id = 1:6, v1 = c("a", "a", "c", NA, "g", "h"), v2 = c("z", "y", "a", NA, "a", "g"), stringsAsFactors=F) I have a specific value that I want to find across a set of defined columns and I want to identify the position it is located in. The fields I am searching are characters and the trick is that the value I am looking for might not exist. In addition, null strings are also present in the dataset. Assuming I knew how to do this, the variable position indicates the values I would like returned. > df id v1 v2 position 1 1 a z 1 2 2 a y 1 3 3 c a 2 4 4 <NA> <NA> 99 5 5 g a 2 6 6 h g 99 The general rule is that I want to find the position of value "a", and if it is not located or if v1 is missing, then I want 99 returned. In this instance, I am searching across v1 and v2, but in reality, I have 10 different variables. It is also worth noting that the value I am searching for can only exist once across the 10 variables. What is the best way to generate this recode? Many thanks in advance.

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• Python - Checking for membership inside nested dict

  - by victorhooi

  heya, This is a followup questions to this one: http://stackoverflow.com/questions/2901422/python-dictreader-skipping-rows-with-missing-columns Turns out I was being silly, and using the wrong ID field. I'm using Python 3.x here. I have a dict of employees, indexed by a string, "directory_id". Each value is a nested dict with employee attributes (phone number, surname etc.). One of these values is a secondary ID, say "internal_id", and another is their manager, call it "manager_internal_id". The "internal_id" field is non-mandatory, and not every employee has one. (I've simplified the fields a little, both to make it easier to read, and also for privacy/compliance reasons). The issue here is that we index (key) each employee by their directory_id, but when we lookup their manager, we need to find managers by their "internal_id". Before, when employee.keys() was a list of internal_ids, I was using a membership check on this. Now, the last part of my if statement won't work, since the internal_ids is part of the dict values, instead of the key itself. def lookup_supervisor(manager_internal_id, employees): if manager_internal_idis not None and manager_internal_id!= "" and manager_internal_id in employees.keys(): return (employees[manager_internal_id]['mail'], employees[manager_internal_id]['givenName'], employees[manager_internal_id]['sn']) else: return ('Supervisor Not Found', 'Supervisor Not Found', 'Supervisor Not Found') So the first question is, how do I check whether the manager_internal_id is present in the dict's values. I've tried substituting employee.keys() with employee.values(), that didn't work. Also, I'm hoping for something a little more efficient, not sure if there's a way to get a subset of the values, specifically, all the entries for employees[directory_id]['internal_id']. Hopefully there's some Pythonic way of doing this, without using a massive heap of nested for/if loops. My second question is, how do I then cleanly return the required employee attributes (mail, givenname, surname etc.). My for loop is iterating over each employee, and calling lookup_supervisor. I'm feeling a bit stupid/stumped here. def tidy_data(employees): for directory_id, data in employees.items(): # We really shouldnt' be passing employees back and forth like this - hmm, classes? data['SupervisorEmail'], data['SupervisorFirstName'], data['SupervisorSurname'] = lookup_supervisor(data['manager_internal_id'], employees) Thanks in advance =), Victor

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• Creating one row of information in excel using a unique value

  - by user1426513

  This is my first post. I am currently working on a project at work which requires that I work with several different worksheets in order to create one mail master worksheet, as it were, in order to do a mail merge. The worksheet contains information regarding different purchases, and each purchaser is identified with their own ID number. Below is an example of what my spreadsheet looks like now (however I do have more columns): ID Salutation Address ID Name Donation ID Name Tickets 9 Mr. John Doe 123 12 Ms. Jane Smith 100.00 12 Ms.Jane Smith 300.00 12 Ms. Jane Smith 456 22 Mr. Mike Man 500.00 84 Ms. Jo Smith 300.00 What I would like to do is somehow sort my data so that everythign with the same unique identifier (ID) lines up on the same row. For example ID 12 Jane Smith - all the information for her will show up under her name matched by her ID number, and ID 22 will match up with 22 etc... When I merged all of my spreadsheets together, I sorted them all by ID number, however my problem is, not everyone who made a donation bought a ticket or some people just bought tickets and nothing us, so sorting doesn't work. Hopefully this makes sense. Thanks in advance.

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• SQL Server INSERT ... SELECT Statement won't parse

  - by Jim Barnett

  I am getting the following error message with SQL Server 2005 Msg 120, Level 15, State 1, Procedure usp_AttributeActivitiesForDateRange, Line 18 The select list for the INSERT statement contains fewer items than the insert list. The number of SELECT values must match the number of INSERT columns. I have copy and pasted the select list and insert list into excel and verified there are the same number of items in each list. Both tables an additional primary key field with is not listed in either the insert statement or select list. I am not sure if that is relevant, but suspicious it may be. Here is the source for my stored procedure: CREATE PROCEDURE [dbo].[usp_AttributeActivitiesForDateRange] ( @dtmFrom DATETIME, @dtmTo DATETIME ) AS BEGIN SET NOCOUNT ON; DECLARE @dtmToWithTime DATETIME SET @dtmToWithTime = DATEADD(hh, 23, DATEADD(mi, 59, DATEADD(s, 59, @dtmTo))); -- Get uncontested DC activities INSERT INTO AttributedDoubleClickActivities ([Time], [User-ID], [IP], [Advertiser-ID], [Buy-ID], [Ad-ID], [Ad-Jumpto], [Creative-ID], [Creative-Version], [Creative-Size-ID], [Site-ID], [Page-ID], [Country-ID], [State Province], [Areacode], [OS-ID], [Domain-ID], [Keyword], [Local-User-ID], [Activity-Type], [Activity-Sub-Type], [Quantity], [Revenue], [Transaction-ID], [Other-Data], Ordinal, [Click-Time], [Event-ID]) SELECT [Time], [User-ID], [IP], [Advertiser-ID], [Buy-ID], [Ad-ID], [Ad-Jumpto], [Creative-ID], [Creative-Version], [Creative-Size-ID], [Site-ID], [Page-ID], [Country-ID], [State Province], [Areacode], [OS-ID], [Domain-ID], [Keyword], [Local-User-ID] [Activity-Type], [Activity-Sub-Type], [Quantity], [Revenue], [Transaction-ID], [Other-Data], REPLACE(Ordinal, '?', '') AS Ordinal, [Click-Time], [Event-ID] FROM Activity_Reports WHERE [Time] BETWEEN @dtmFrom AND @dtmTo AND REPLACE(Ordinal, '?', '') IN (SELECT REPLACE(Ordinal, '?', '') FROM Activity_Reports WHERE [Time] BETWEEN @dtmFrom AND @dtmTo EXCEPT SELECT CONVERT(VARCHAR, TripID) FROM VisualSciencesActivities WHERE [Time] BETWEEN @dtmFrom AND @dtmTo); END GO

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• Group / User based security. Table / SQL question

  - by Brett

  Hi, I'm setting up a group / user based security system. I have 4 tables as follows: user groups group_user_mappings acl where acl is the mapping between an item_id and either a group or a user. The way I've done the acl table, I have 3 columns of note (actually 4th one as an auto-id, but that is irrelevant) col 1 item_id (item to access) col 3 user_id (user that is allowed to access) col 3 group_id (group that is allowed to access) So for example item1, peter, , item2, , group1 item3, jane, , so either the acl will give access to a user or a group. Any one line in the ACL table with either have an item - user mapping, or an item group. If I want to have a query that returns all objects a user has access to, I think I need to have a SQL query with a UNION, because I need 2 separate queries that join like.. item - acl - group - user AND item - acl - user This I guess will work OK. Is this how its normally done? Am I doing this the right way? Seems a little messy. I was thinking I could get around it by creating a single user group for each person, so I only ever deal with groups in my SQL, but this seems a little messy as well..

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• Presentation Issue in an Unordered List

  - by phreeskier

  I'm having an issue with correctly presenting items in an unordered list. The labels are floating left and the related spans that are long in length are wrapping and showing below the label. I need a solution that keeps the related spans in their respective columns. In other words, I don't want long spans to show under the labels. What property can I take advantage of so that I get the desired layout in all of the popular browsers, including IE6? Thanks in advance for the help. My code is as follows: <ul> <li> <label>Name</label> <span><%= Html.Encode(Model.Name) %></span> </li> <li> <label>Entity</label> <span><%= Html.Encode(Model.Entity) %></span> </li> <li> <label>Phone</label> <span><%= Html.Encode(Model.Phone) %></span> </li> </ul> My CSS styling is as follows: ul { display:block; list-style-type:none; margin:0; padding:0; } ul li label { float:left; width:100px; }

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• using dummy row with NOT NULL to solve DEFAULT NULL

  - by Tony38

  I know having DEFAULT NULLS is not a good practice but I have many optional lookup values which are FK in the system so to solve this issue here is what i am doing: I use NOT NULL for every FK / lookup colunms. I have the first row in every lookup table which is PK id = 1 as a dummy row with just "none" in all the columns. This way I can use NOT NULL in my schema and if needed reference to the none row values PK =1 for FKs which do not have any lookup value. Is this a good design or any other work arounds? EDIT: I have: Neighborhood table Postal table. Every neighborhood has a city, so the FK can be NOT NULL. But not every postal code belongs to a neighborhood. Some do, some don't depending on the country. So if i use NOT NULL for the FK between postal and neighborhood then I will be screwed as there has to be some value entered. So what i am doing in essence is: have a row in every table to be a dummy row just to link the FKs. This way row one in neighborhood table will be: n_id = 1 name =none etc... In postal table I can have: postal_code = 3456A3 FK (city) = Moscow FK (neighborhood_id)=1 as a NOT NULL. If I don't have a dummy row in the neighborhood lookup table then I have to declare FK (neighborhood_id) as a Default null column and store blanks in the table. This is an example but there is a huge number of values which will have blanks then in many tables.

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• How to index a table with a Type 2 slowly changing dimension for optimal performance

  - by The Lazy DBA

  Suppose you have a table with a Type 2 slowly-changing dimension. Let's express this table as follows, with the following columns: * [Key] * [Value1] * ... * [ValueN] * [StartDate] * [ExpiryDate] In this example, let's suppose that [StartDate] is effectively the date in which the values for a given [Key] become known to the system. So our primary key would be composed of both [StartDate] and [Key]. When a new set of values arrives for a given [Key], we assign [ExpiryDate] to some pre-defined high surrogate value such as '12/31/9999'. We then set the existing "most recent" records for that [Key] to have an [ExpiryDate] that is equal to the [StartDate] of the new value. A simple update based on a join. So if we always wanted to get the most recent records for a given [Key], we know we could create a clustered index that is: * [ExpiryDate] ASC * [Key] ASC Although the keyspace may be very wide (say, a million keys), we can minimize the number of pages between reads by initially ordering them by [ExpiryDate]. And since we know the most recent record for a given key will always have an [ExpiryDate] of '12/31/9999', we can use that to our advantage. However... what if we want to get a point-in-time snapshot of all [Key]s at a given time? Theoretically, the entirety of the keyspace isn't all being updated at the same time. Therefore for a given point-in-time, the window between [StartDate] and [ExpiryDate] is variable, so ordering by either [StartDate] or [ExpiryDate] would never yield a result in which all the records you're looking for are contiguous. Granted, you can immediately throw out all records in which the [StartDate] is greater than your defined point-in-time. In essence, in a typical RDBMS, what indexing strategy affords the best way to minimize the number of reads to retrieve the values for all keys for a given point-in-time? I realize I can at least maximize IO by partitioning the table by [Key], however this certainly isn't ideal. Alternatively, is there a different type of slowly-changing-dimension that solves this problem in a more performant manner?

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• SQL: select rows with the same order as IN clause

  - by Andrea3000

  I know that this question has been asked several times and I've read all the answer but none of them seem to completely solve my problem. I'm switching from a mySQL database to a MS Access database with MS SQL. In both of the case I use a php script to connect to the database and perform SQL queries. I need to find a suitable replacement for a query I used to perform on mySQL. I want to: perform a first query and order records alphabetically based on one of the columns construct a list of IDs which reflects the previous alphabetical order perform a second query with the IN clause applied with the IDs' list and ordered by this list. In mySQL I used to perform the last query this way: SELECT name FROM users WHERE id IN ($name_ids) ORDER BY FIND_IN_SET(id,'$name_ids') Since FIND_IN_SET is available only in mySQL and CHARINDEX and PATINDEX are not available from my php script, how can I achieve this? I know that I could write something like: SELECT name FROM users WHERE id IN ($name_ids) ORDER BY CASE id WHEN ... THEN 1 WHEN ... THEN 2 WHEN ... THEN 3 WHEN ... THEN 4 END but you have to consider that: IDs' list has variable length and elements because it depends on the first query that list can easily contains thousands of elements Have you got any hint on this? Is there a way to programmatically construct the ORDER BY CASE ... WHEN ... statement? Is there a better approach since my list of IDs can be big?

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• How to Specify Columntype in fluent nHibernate?

  - by Bipul

  I have a class CaptionItem public class CaptionItem { public virtual int SystemId { get; set; } public virtual int Version { get; set; } protected internal virtual IDictionary<string, string> CaptionValues {get; private set;} } I am using following code for nHibernate mapping Id(x => x.SystemId); Version(x => x.Version); Cache.ReadWrite().IncludeAll(); HasMany(x => x.CaptionValues) .KeyColumn("CaptionItem_Id") .AsMap<string>(idx => idx.Column("CaptionSet_Name"), elem => elem.Column("Text")) .Not.LazyLoad() .Cascade.Delete() .Table("CaptionValue") .Cache.ReadWrite().IncludeAll(); So in database two tables get created. One CaptionValue and other CaptionItem. In CaptionItem table has three columns 1. CaptionItem_Id int 2. Text nvarchar(255) 3. CaptionSet_Name nvarchar(255) Now, my question is how can I make the columnt type of Text to nvarchar(max)? Thanks in advance.

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• Oracle ODBC x64 - getting 0 when selecting a number(9) column

  - by MatsL

  I'm having a really weird problem with a third party web service that uses an ODBC connection to Oracle 10.2.0.3.0. I've written a .NET client that generates the same SQL as the web service so I can find out what's going on. The web service is hosted by IIS 6 that's in x64 mode so we use Oracle x64 client. The oracle client version is 10.2.0.1.0. I have a table that looks like this (I've removed some columns and names): SQL> describe tablename; Name Null? Type ----------------------------------------- -------- ---------------------------- KOD VARCHAR2(30) ORDNING NUMBER(5) AVGIFT NUMBER(9) I then in SQL*Plus issue the following statement: SELECT KOD as kod, AVGIFT as riskPoang FROM tablename Where upper(KODTYP) = 'OBJLIVSV_RISKVERKSAMTYP' ORDER BY ORDNING And I get the following result: KOD RISKPOANG ------------------------------ ---------- Hög risk 55 Mellan risk 35 Låg risk 15 Mycket låg risk 5 But when I execute the exact same SQL using the same DSN on the same machine I get this: Values Kod: Hög risk RiskPoäng: 0 Kod: Mellan risk RiskPoäng: 0 Kod: Låg risk RiskPoäng: 0 Kod: Mycket låg risk RiskPoäng: 0 If I first cast the number to varchar and then back again to number, like this: SELECT KOD as kod, to_number(to_char(AVGIFT, '99'), '9999999999') as riskPoang FROM tablename Where upper(KODTYP) = 'OBJLIVSV_RISKVERKSAMTYP' ORDER BY ORDNING I get the correct result: Values Kod: Hög risk RiskPoäng: 55 Kod: Mellan risk RiskPoäng: 35 Kod: Låg risk RiskPoäng: 15 Kod: Mycket låg risk RiskPoäng: 5 Has anyone else experiences this? It's incredibly annoying and I'm completely stuck and not sure what to do next. We have a third party web service that use these tables so I must get the original SQL-statement to work since I can't modify its code. And pointers are greatly appreciated! :-) Best regards, Mats

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• How to display objects with dynamic fields in wpf data grid?

  - by Oliver Hanappi

  Hi! I want to display and edit some objects in a WPF data grid and I'm looking for a good way to do so. All objects I want to display have the same fields, but every execution the fields of my objects can differ. Here is a piece of the interface to illustrate what I mean: public interface IMyObject { IEnumerable<string> GetFieldNames(); IEnumerable<Type> GetFieldTypes(); object GetField(string name); void SetField(string name, object value); } How can I generate a data grid which displays this kind of objects? I thought of XAML generation to define the columns, but I'm still facing the problem of accessing the fields. I think I could realize this with value converters, another option would be to dynamically create a type which exposes the dynamic fields with properties. Are there any other ways and which should I favor? I'm keen on hearing your opinions. Best Regards, Oliver Hanappi

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