Standard Error Handling

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Every time a SQL statement is executed, it returns a status indicator in the ­SQLCODE variable, which is declared automatically for SQL programs during preprocessing with gpre. The following table summarizes possible SQLCODE values and their meanings:

Possible SQLCODE values

Value	Meaning
0	Success
1–99	Warning or informational message
100	End of file (no more data)
< 0	Error. Statement failed to complete

To trap and respond to run-time errors, SQLCODE should be checked after each SQL operation. There are three ways to examine SQLCODE and respond to errors:

• Use WHENEVER statements to automate checking SQLCODE and handle errors when they occur.
• Test SQLCODE directly after individual SQL statements.
• Use a judicious combination of WHENEVER statements and direct ­testing.

Each method has advantages and disadvantages, described fully in the remainder of this chapter.

Topics

• WHENEVER Statements
• Testing SQLCODE Directly
• Combining Error-handling Techniques
• Guidelines for Error Handling