SIGNAL and RESIGNAL
Explore how SQL's SIGNAL and RESIGNAL statements enable you to raise and manage errors within stored procedures. Learn to validate data, halt processes gracefully, and customize error messages for clearer communication with users and handlers.
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SIGNAL and RESIGNAL
SIGNAL statement is a way to return an error to a handler or a client application. The sender can choose which error characteristics (like the error number or message text) to return. SIGNAL provides a way to handle unexpected events that may lead to application termination. By raising errors, we can provide information to the error handler for a graceful exit rather than an abrupt termination.
The SIGNAL keyword is used to raise errors. It is followed by a SQLSTATE value or a named condition defined with a SQLSTATE value. SIGNAL cannot be associated with a MySQL error code. The SQLSTATE value 45000 is generic and can be used to catch any un-handled user defined exceptions.
The SET clause is used to return information about the error. The diagnostic information about an error includes MYSQL_ERRNO, MESSAGE_TEXT, CLASS_ORIGIN, SUBCLASS_ORIGIN, CONSTRAINT_CATALOG, CONSTRAINT_SCHEMA, CONSTRAINT_NAME, CATALOG_NAME, SCHEMA_NAME, TABLE_NAME, COLUMN_NAME, and CURSOR_NAME. The sender can choose to send more than one of these items as a comma separated list.
Syntax
SIGNAL SQLSTATE | condition_name
SET condition_information_item1 = val1, condition_information_item2 = val2, … ;
The RESIGNAL statement is similar to the SIGNAL statement. It is ...