MySQL 8.0

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select version();

version()

8.0.27

CREATe TABLE TEST(i int);
INSERT INtO TEST VALUES (0),(1),(2),(3);
CREATE PROCEDURE do_thing (OUT success BOOLEAN)     

DETERMINISTIC

DECLARE EXIT HANDLER FOR SQLEXCEPTION BEGIN SET success := FALSE; ROLLBACK; END;   # rollback on any error
DECLARE EXIT HANDLER FOR SQLWARNING  BEGIN SET success := FALSE; ROLLBACK; END;     # rollback on any warning
BEGIN   
START TRANSACTION;

       SELECT * FROM TEST;

COMMIT;
SET success := TRUE;  
END

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE EXIT HANDLER FOR SQLEXCEPTION BEGIN SET success := FALSE; ROLLBACK; END;' at line 5

CREATE PROCEDURE do_thing (OUT success BOOLEAN)     

DETERMINISTIC

BEGIN   
      DECLARE EXIT HANDLER FOR SQLEXCEPTION BEGIN SET success := FALSE; ROLLBACK; END;   # rollback on any error
      DECLARE EXIT HANDLER FOR SQLWARNING  BEGIN SET success := FALSE; ROLLBACK; END;   # rollback on any warning
START TRANSACTION;

       SELECT 5/i FROM TEST WHERE i>=1;

COMMIT;
SET success := TRUE;  
END

CALL do_thing(@success);
SELECT @success;

5/i

5.0000

2.5000

1.6667

@success

1

DROP PROCEDURE do_thing ;  
CREATE PROCEDURE do_thing (OUT success BOOLEAN)     

DETERMINISTIC

BEGIN   
      DECLARE EXIT HANDLER FOR SQLEXCEPTION BEGIN SET success := FALSE; ROLLBACK; END;   # rollback on any error
      DECLARE EXIT HANDLER FOR SQLWARNING  BEGIN SET success := FALSE; ROLLBACK; END;   # rollback on any warning
START TRANSACTION;

       SELECT 5/i FROM TEST WHERE i>=0;

COMMIT;
SET success := TRUE;  
END
CALL do_thing(@success);
SELECT @success;

5/i

null

5.0000

2.5000

1.6667

@success

0