In addition to using SQL Optimizer to generate alternative statements, you can create user defined alternatives. You can create user defined alternatives using SQL text from your original SQL statement or from SQL text of an alternative SQL Optimizer generated.
Note: This topic focuses on information that may be unfamiliar to you. It does not include all step and field descriptions.
To create a user defined alterative
Enter the SQL statement in the in the Alternative Details pane.
Click .
Edit the statement in the SQL Text pane to create a user defined alternative.
Note: To create a user defined alternative using SQL text of an alternative SQL Optimizer generated, right-click an alternative and select User Alternative.
Caution: SQL Optimizer does not check that user defined alternatives are semantically equivalent to your original SQL statement. Review the execution statistics for user defined alternatives to compare the results with your original statement. See View Execution Statistics for more information.
You need to define the values of SQL statement variables before you optimize the statement. The Set Bind Variables window displays automatically when you use SQL Optimizer for a statement with variables.
Troubleshooting: If the Set Bind Variables window displays when you optimize a statement without variables, make sure you spelled the column and table names correctly, you selected the correct database or user, and you selected a table or column that exists in the database.
Note: This topic focuses on information that may be unfamiliar to you. It does not include all step and field descriptions.
To set a bind variable
Enter a SQL statement with a bind variable.
Note: SQL Optimizer currently supports the following bind variables data type:
CHAR
Click .
Review the following for additional information:
Bind Variables List | Description |
Datatype |
Click |
Null |
Select the checkbox if the value for the variable is null. |
Variable Value |
Enter a value for the variable. |
Browse Data | Description |
SELECT |
Click Note: SQL Optimizer selects the All Columns checkbox by default. |
FROM |
Click Tip: Click |
WHERE |
Enter a WHERE clause or click |
ORDER BY |
Enter a ORDER BY clause or click |
Use the Alternatives pane to review the SQL text and execution plan for the alternatives SQL Optimizer generates. You can also review the run-time statistics for your original SQL statement and the alternatives after you execute the statements.
Note: This topic focuses on information that may be unfamiliar to you. It does not include all step and field descriptions.
To review details for an alternative
Select an alternative in the Alternatives pane.
Review details for the alternative in the Alternative Details and Execution Plan panes.
Automatically Optimize SQL Statements
The text editor is used to display the SQL text of the selected alternative. When there’s only original alternative or the selected alternative is user defined, the SQL text can be edited. Otherwise, it’s read-only.
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