PolarDB:Exception handling

By default, any error occurring in an SPL program aborts execution of the program. You can trap errors and recover from them by using a BEGIN block that has an EXCEPTION section.

The corresponding syntax is an extension of the normal syntax for a BEGIN block:

[ DECLARE
    declarations ]
  BEGIN
    statements
  EXCEPTION
    WHEN condition [ OR condition ]... THEN
      handler_statements
  [ WHEN condition [ OR condition ]... THEN
      handler_statements ]...
  END;

If no error occurs, this form of block simply executes all the statements, and then control passes to the next statement after END. If an error occurs within the statements, further processing of the statements is abandoned, and control passes to the EXCEPTION list. The list is searched for the first condition matching the error that occurred. If a match is found, the corresponding handler_statements are executed, and then control passes to the next statement after END. If no match is found, the error propagates out as though the EXCEPTION clause did not exist. The error can be caught by an enclosing block with EXCEPTION. If no enclosing block exists, the error aborts processing of the subprogram.

The special condition name OTHERS matches every error type. Condition names are not case-sensitive.

If a new error occurs within the selected handler_statements, the error cannot be caught by this EXCEPTION clause, but is propagated out. A surrounding EXCEPTION clause can catch the error.

The following table lists the condition names that may be used.