SQL statements must be prepared during the program preparation process before the program is executed. This process is called binding. The SQL Preprocessor prepares the SQL portions of a source program for execution.
CA Datacom/DB delays some decisions which impact the method used to execute an SQL statement until execution time if information required to make the best decision is not available until execution time. This technique is called phased binding. In effect, the binding process is performed in discrete phases and one of those phases does not occur until execution time.
For SQL statements embedded in a host language, such as COBOL, binding is performed when the program is preprocessed. For SQL statements executed through CA Dataquery, binding occurs during the validation step. For the CA Datacom Datadictionary, binding occurs automatically when SQL statements are executed.
When a statement is prepared, any dependencies of that statement on table or view definitions are recorded in the CA Datacom Datadictionary. If any dependent objects are changed, the related statement is marked invalid and must be rebound before it can be executed again.
The SQL Manager automatically attempts a rebind when an invalid statement is executed. Rebinding can also be requested in advance. For more information, see CA Datacom/DB SQL Preprocessors.
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