C# Datasets (.NET2)
CodeGuru Home VC++ / MFC / C++ .NET / C# Visual Basic VB Forums Developer.com
Results 1 to 2 of 2

Thread: C# Datasets (.NET2)

  1. #1
    Join Date
    Sep 2010
    Posts
    13

    C# Datasets (.NET2)

    Hi All,

    I am having a problem updating using the C# datasets that is driving me mad. This should be a simple task, but I am getting some strange behaviour...I am sure I am doing something stupid but not sure what.

    Basically I have three tables, TEMPLATES, TEMPLATE_EXPRESSIONS and GENERIC_EXPRESSIONS (in an Access 2003 database). The template_expressions table contains a link between templates and generic_expresions so that multiple templates can use the same generic_expressions. Built into this is a locking function on GENERIC_EXPRESSIONS, which sets a session id value to ensure multiple users can't edit at the same time.

    What I wish to do is update GENERIC_EXPRESSIONS so that the locking status is set to the session id for all items for a particular template. I have created an update command on my data adapter, which looks like this:

    Code:
    UPDATE GENERIC_EXPRESSIONS
    SET ITEM_LOCK = @sessionId
    WHERE EXPRESSION_ID IN (SELECT EXPRESSION_ID FROM TEMPLATE_EXPRESSIONS WHERE TEMPLATE_ID = @templateId)
    The command is called SetTemplateLock (sessionId, templateId) and the two parameters are both defined as int32 and in the correct order when I view them.

    All seems pretty straightforward right? When I run it I use the following code:

    Code:
    GENERIC_EXPRESSIONSTableAdapter.SetTemplateLock(pSessionId, pTemplateId);
    Now I have confirmed that the values for pSessionId and pTemplateId are correct, but what happens is the following:

    Code:
    UPDATE GENERIC_EXPRESSIONS
    SET ITEM_LOCK = @templateId
    WHERE EXPRESSION_ID IN (SELECT EXPRESSION_ID FROM TEMPLATE_EXPRESSIONS WHERE TEMPLATE_ID = @sessionId)
    Obviously this updates completely the wrong rows.

    I have various other queries that use a similar method (and work correctly) and the only difference with this one is that it reads data in from a sub-table.

    Anyone seen any similar or can spot something stupid that I have done?

    Thanks



    Andrew

  2. #2
    Join Date
    Sep 2010
    Posts
    13

    (RESOLVED) C# Datasets (.NET2)

    Hello,

    Well I have managed to resolve the problem and I think I know why it is occuring. It would appear that the statement within the brackets is parsed first, i.e.

    (SELECT EXPRESSION_ID FROM TEMPLATE_EXPRESSIONS WHERE TEMPLATE_ID = @templateId)

    This being the case templateId would be the first parameter and sessonId the second. I have changed the parameters round and lo and behold it works!

    Cheers



    Andrew

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Azure Activities Information Page

Windows Mobile Development Center


Click Here to Expand Forum to Full Width

This is a CodeGuru survey question.


Featured


HTML5 Development Center