Programming Notes 

To optimize your SAP DB application program, remember the following programming notes:

·        In SELECT statements, identify the columns that you want to select.

·        Use key specifications to identify the table rows that need to be processed. You can determine key columns from the system tables.

·        SELECT statements with multiple result rows with no ORDER clause do not specify the order in which the table rows are read from the database table. In this case, the logic of your application program cannot assume that there is a specified order.,

·        You can use the SINGLE SELECT statement to process individual rows in the SQL mode INTERNAL.

·        Note the different way of handling named result tables (CURSOR) in the different SQL modes.

For information on the special features of the SQL mode ORACLE in the SAP DB database system, see the documentation SQL Mode ORACLE: SAP DB.

·        Inform yourself about the user and role concept of the SAP DB database system.

·        Execute a RELEASE statement as the final SQL statement in your application program. This releases the resources needed by the precompiler runtime environment.

·        In the SAP DB database system, remember that DDL statements such as CREATE TABLE are also subject to the transaction concept, which means that they can be undone or that they must be completed with a COMMIT statement.

·        Read the information about the locks in the database, and define a suitable isolation level for your statements.

·        Program reactions to possible TIMEOUT messages. You can do this by, for example, querying the structure component sqlcode after each SQL statement (see Database System Messages).

For more information on the meaning of the optimum SQL statements and the available options, see Optimizer: SAP DB.