throw
NAME
throw(): Disrupt execution with errorTYPE
ProcedureDESCRIPTION
Issues an error at the point of invocation, providing with an error message.
This is done by invoking an invalid command on the server. The result of such invocation will break execution of calling code. If this routine is invoked from another routine, the entire call stack is aborted. If this routine is called during a transaction, the transaction aborts and rolls back.
On a MySQL >= 5.5 server this routine calls upon SIGNAL. On a 5.1 server it generates a statement which reads from an invalid table, producing an awkward yet informative error message.
SYNOPSIS
throw(error_message VARCHAR(1024) CHARSET utf8) NO SQL
Input:
- error_message: a message to be displayed within error statement.
Output:
- @common_schema_error: The procedure sets this variable to the error_message supplied.
EXAMPLES
Invoke throw() directly, on a 5.1 MySQL server:
mysql> call throw('Unknown variable type');
ERROR 1644 (91100): Unknown variable type
mysql> SELECT @common_schema_error;
+-----------------------+
| @common_schema_error |
+-----------------------+
| Unknown variable type |
+-----------------------+
Invoke throw() directly, on a 5.1 MySQL server:
mysql> call throw('Unknown variable type');
ERROR 1146 (42S02): Table 'error.Unknown variable type' doesn't exist
Invoke a syntactically invalid script; the run() routine and subroutines validate script syntax and call upon throw():
mysql> call run('{set @x := 3; ; ; }');
ERROR 1103 (42000): Incorrect table name 'QueryScript error: [Empty statement not allowed. Use {} instead] at 16: "; ; }"'
mysql> SELECT @common_schema_error;
+---------------------------------------------------------------------------------+
| @common_schema_error |
+---------------------------------------------------------------------------------+
| QueryScript error: [Empty statement not allowed. Use {} instead] at 16: "; ; }" |
+---------------------------------------------------------------------------------+