Use the WHERE clause to combine data sources Limit results by using criteria When you want to use data to limit the number of records that are returned in a query, you can use criteria. Query criteria are a type of expression. The following table shows some sample criteria and explains how they work. It includes only those records where the Price or UnitsInStock field contains a value greater than 25 and less than
Any forms, reports, queries, or code that previously worked with the original Office Access tables are automatically connected to the new SQL Server tables.
In an application that uses linked SQL Server tables, two different database engines are at work: The interaction of these two engines can sometimes yield results that are inferior to those obtained by using only the Jet database engine with native Office Access tables.
This white paper discusses several of these issues and presents strategies for resolving them. Most of these issues relate to performance or updatability. Although performance does often improve, there are many cases where it remains the same or even degrades.
In some cases, performance of certain queries degrades to an unacceptable level.
The major cause of query performance degradation is when a query involving very large tables requires that all of the data from one or more tables be downloaded to the client. This can happen even when joins or criteria appear to limit the result set to a small number of records.
This occurs because sometimes the Office Access database engine determines that it cannot submit an entire query to SQL Server. Instead, it submits multiple queries, often including queries that request all of the rows in a table, and then it combines or filters the data on the client.
If the criteria require local processing, even queries that should return only selected rows from a single table can require that all the rows in the table be returned. The primary strategy for improving performance is to minimize the amount of data returned to the Office Access client and maximize the amount of processing that occurs on the server.
To accomplish this, you need to be able to analyze the SQL commands that Office Access is submitting. To listen in on the conversation from the server side, you can open the SQL Server Profiler and create a new trace.
Select a template that shows TSQL to see all the statements being processed by the server. From the client side, you can edit a Microsoft Windows registry setting that allows you to see the commands that the Office Access database engine is submitting to ODBC. As always, be very careful when editing the Windows registry.
For more information on backing up and editing the registry, see How to Modify the Windows Registry. From the Windows Start menu, select Run. Type Regedit to open the Registry Editor.
If you are using a version of Office Access prior to Office Accessnavigate to the following registry key, which appears as a folder in the Registry Editor. If you are using Office Accessnavigate to the following registry key. If Office Access is open when you make this change, you must close and reopen Office Access for the change to take effect.
After making this change in the registry, queries submitted to any ODBC data source are logged in a text file named Sqlout.
Unless you delete this file or its contents, it continues to grow as new queries are executed and the tracing activity degrades performance.
It is very important to return to the Registry Editor and turn the feature off by changing the TraceSQLMode setting back to 0 when you are done testing. Running SQL Profiler also has a negative impact on performance, so try to avoid using it on a production server and close your Profiler traces when you are done testing.
Before you can make productive use of these diagnostic tools, you must understand how Office Access interacts with SQL Server. Without that understanding, the SQL statements that you see in Profiler traces and in Sqlout logs can be quite puzzling.
Suppliers, and that explicitly names the three columns in the table. Instead, both the Sqlout. The following is what is written to Sqlout.A SQL JOIN combines records from two tables.
A JOIN locates related column values in the two tables.
A query can contain zero, one, or multiple JOIN operations. SQL FULL OUTER JOIN Keyword The FULL OUTER JOIN keyword return all records when there is a match in either left (table1) or right (table2) table records. Note: FULL OUTER JOIN can potentially return very large result-sets!
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Most SQL texts attempt to serve as an encyclopedic reference on SQL syntax -- an approach that is counterproductive. Thus far in this tips series on Access and SQL Server we have created an ODBC Data Source Name (DSN) using the OLEDB driver, created a System DSN for the new SNAC (SQL Native Client) driver and created linked tables in Access by using the SNAC DSN.
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Andy Baron. November Applies to: Microsoft SQL Server Summary: One way to create applications that use Microsoft Office Access for creating user interfaces and that use Microsoft SQL Server for data storage is to link Office Access tables to SQL Server tables.
This is the type of application created by using the SQL Server Migration Assistant for Office Access.