FIX: Problems occur when connecting to SQL Server from ADO application

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Article ID: 300519 - View products that this article applies to.
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When you are using Microsoft Data Access Components (MDAC) version 2.6 from a client application to connect to a SQL Server 7.0 database, the client application may start to experience login timeouts, "Timeout expired" errors, or general network errors. This occurs when the client application is experiencing a high volume of connect and disconnect activity and a large portion of the connections are invalid. Pooling in the Microsoft Data Access Components

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
166083 INF: How to enable connection pooling in an OLE DB application
228843 How to implement session pooling from Visual Basic ADO program


To work around this problem, Microsoft recommends that you use MDAC OLEDB/ODBC pooling functionality. This will reduce the number of physical connections that are open and connection attempts being made to the database and should prevent the problem from occurring.

This problem also does not occur when you are connecting to a SQL Server 2000 database.

SQL Server 7.0

To resolve this problem, obtain the latest service pack for Microsoft SQL Server 7.0. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
301511 How to obtain the latest SQL Server 7.0 service pack


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

SQL Server 7.0
This problem was first corrected in Microsoft SQL Server 7.0 Service Pack 4.


Article ID: 300519 - Last Review: February 27, 2014 - Revision: 5.1
  • Microsoft SQL Server 7.0 Standard Edition
  • Microsoft Data Access Components 2.6
  • Microsoft Data Access Components 2.7
kbnosurvey kbarchive kbbug kbfix kbsqlserv700presp4fix KB300519

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