Exception using TRY CATCH in mysql stored procedure - mysql

Question

Following is the procedure in which i am trying to catch the exception, if there is any in stored procedure
DROP PROCEDURE IF EXISTS test;
DELIMITER //
CREATE PROCEDURE test( IN contextFilter TEXT)
BEGIN TRY
set #sub_query = 'SELECT id from test_table';
PREPARE stmt_query FROM #sub_query;
SELECT #sub_query;
EXECUTE stmt_query;
DEALLOCATE PREPARE stmt_query;
END TRY //
BEGIN CATCH
SELECT ERROR_NUMBER() AS ErrorNumber,ERROR_MESSAGE() AS ErrorMessage;
END CATCH
DELIMITER ;
When i try to source the stored procedure , i am getting the following exception
source /home/test.sql;
Query OK, 0 rows affected (0.01 sec)
ERROR 1064 (42000) at line 5 in file: '/home/test.sql': You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'set #sub_query = 'SELECT id from test_table';
PREPARE stmt_query FROM #' at line 5
ERROR 1064 (42000) at line 17 in file: '/home/test.sql': You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'CATCH
SELECT ERROR_NUMBER() AS ErrorNumber,ERROR_MESSAGE() AS ErrorMessage;
' at line 1

Answer 1

The post above helped me, but I still had to do some research on my own. In order to provide a complete example you can see below. This code will declare a handler for "catching" SQLExceptions and then exit if it occurs.
DROP PROCEDURE IF EXISTS `SP_TEST`;
DELIMITER //
CREATE PROCEDURE `SP_TEST`()
BEGIN
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
GET DIAGNOSTICS CONDITION 1 #p1 = RETURNED_SQLSTATE, #p2 = MESSAGE_TEXT;
SELECT CONCAT(#p1, ':', #p2);
END;
SELECT FAKE_COLUMN FROM MY_TABLE;
END //
CALL SP_TEST;
This works in mySQL version 5.7 and hope it helps you.

Answer 2

In mySql, there is no try... catch block like in Java. You can I handle errors through error handling?
Syntax
DECLARE handler_action HANDLER
FOR condition_value [, condition_value] ...
statement
handler_action:
CONTINUE
| EXIT
| UNDO
condition_value:
mysql_error_code
| SQLSTATE [VALUE] sqlstate_value
| condition_name
| SQLWARNING
| NOT FOUND
| SQLEXCEPTION
The handler_action value indicates what action the handler takes after execution of the handler statement:
CONTINUE: Execution of the current program continues.
EXIT: Execution terminates for the BEGIN ... END compound statement in which the handler is declared. This is true even if the condition occurs in an inner block.
UNDO: Not supported.
For more info go to Official site