Basic processes of the SQL precompiler

You must precompile and compile an application program containing embedded SQL statements before you can run it.

Precompiling of such programs is done by the SQL precompiler. The SQL precompiler scans each statement of the application program source and does the following:

• Looks for SQL statements and for the definition of host variable names. The variable names and definitions are used to verify the SQL statements. You can examine the listing after the SQL precompiler completes processing to see if any errors occurred.
• Verifies that each SQL statement is valid and free of syntax errors. The validation procedure supplies error messages in the output listing that help you correct any errors that occur.
• Validates the SQL statements using the description in the database. During the precompile, SQL statements are checked for valid table, column, and other object references. If a specified object does not exist or you are not authorized to it at the time of the precompile, complete validation will be done at run time. If an object does not exist at run time, an error occurs.
  Notes:

  1. Overrides are processed when retrieving external definitions.
  2. You need some authority (at least *OBJOPR) to any tables or views referred to in the SQL statements in order to validate the SQL statements. The actual authority required to process any SQL statement is checked at run time.
  3. When the RDB parameter is specified on the CRTSQLxxx commands, the precompiler accesses the specified relational database to obtain the table and view descriptions.
• Prepares each SQL statement for compilation in the host language. For most SQL statements, the SQL precompiler inserts a comment and a CALL statement to one of the SQL interface modules. For some SQL statements (for example, DECLARE statements), the SQL precompiler produces no host language statement except a comment.
• Produces information about each precompiled SQL statement. The information is stored internally in a temporary source file member, where it is available for use during the bind process.

To get complete diagnostic information when you precompile, specify either of the following:

• OPTION(*SOURCE *XREF) for CRTSQLxxx (where xxx=CBL, PLI, or RPG)
• OPTION(*XREF) OUTPUT(*PRINT) for CRTSQLxxx (where xxx=CI, CPPI, CBLI, or RPGI)