Accessing a DLL

• Marcelo Trein

  Valued Member

  Points: 70

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  February 4, 2005 at 4:16 am

  #66490

  Hello,

  I have a DLL written in C. How can I access its methods and attributes from the sql code? I am using SQL Server.

  I would appreciate as much detail as possible, since I am a total newb in this matter, but nay help at alçl would be appreciated.

  Thanks in advance,

  Marcelo

• February 7, 2005 at 8:00 am

  This was removed by the editor as SPAM

• achavez

  Old Hand

  Points: 359

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  February 7, 2005 at 11:56 am

  #541004

  Questions -

  • When you say 'written in C' do you mean C++ or C compiled with Visual C++?  The reason I ask is that C-based DLLs don't have 'attributes' or 'methods', they just have functions.

  • Do you have access to the source?

  • Do you have access to VB?

  I have interacted with DLLs in TSQL in a couple of ways.  Using the 'standard' way, the DLLs MUST be COM (OLE Automation) libraries.  Generally these are written in C++, VB, Delphi (among others).  You ineract with the objects defined in the library using the sp_OAxxx procs.  From BOL:

  To create an OLE Automation object

  1. Call sp_OACreate to create the object.
  2. Use the object.

     • Call sp_OAGetProperty to get a property value.
     • Call sp_OASetProperty to set a property to a new value.
     • Call sp_OAMethod to call a method.
     • Call sp_OAGetErrorInfo to get the most recent error information.

  3. Call sp_OADestroy to destroy the object.

  

  Note  All of these steps must be performed within a single Transact-SQL statement batch. All created OLE objects are destroyed automatically at the end of each statement batch.

   

   

  If the library is NOT a COM library, you can make it one given some knowledge (and access to) Visual Basic.

  
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