The difference between set autocommit=0 and start transaction in MySQL

Set autocommit=0 refers to a transaction that is not automatically committed, since the execution of this sentence, each SQL statement or statement block the transaction needs to display "commit" to commit the transaction.

1, whether autocommit is 1 or 0
After START TRANSACTION, only if the commit data will take effect, the rollback will be rolled back.

2, when autocommit is 0 o'clock
Whether or not there is a start TRANSACTION.
Only if the commit data will take effect will it be rolled back after rollback.

3, if the autocommit is 1, and there is no start TRANSACTION.
It is useless to call rollback. Even if the savepoint is set.

Roll back success

Set autocommit =1;delimiter $ $DROP PROCEDURE IF EXISTS  mmmm $$  CREATE definer= ' tms_admin ' @ '% ' PROCEDURE ' mmmm ' () BEGIN          DECLARE t_error INTEGER DEFAULT 0;    DECLARE CONTINUE HANDLER for sqlexception,sqlwarning,not FOUND  SET t_error=1;        START TRANSACTION;    SavePoint P1;              Update T_user Set instance_seq_id = ' tt00006 ';            Update T_user Set instance_seq_id000 = ' tt00007 ';            IF t_error = 1 then                 ROLLBACK to P1;            ELSE                 COMMIT;             END IF; end$ $DELIMITER; Call ' tms_inst_tt00003 '. ' Mmmm ' ();

Set autocommit =0;delimiter $ $DROP PROCEDURE IF EXISTS  mmmm $$  CREATE definer= ' tms_admin ' @ '% ' PROCEDURE ' mmmm ' () BEGIN          DECLARE t_error INTEGER DEFAULT 0;    DECLARE CONTINUE HANDLER for sqlexception,sqlwarning,not FOUND  SET t_error=1;        START TRANSACTION;    SavePoint P1;              Update T_user Set instance_seq_id = ' tt00006 ';            Update T_user Set instance_seq_id000 = ' tt00007 ';            IF t_error = 1 then                 ROLLBACK to P1;            ELSE                 COMMIT;             END IF; end$ $DELIMITER; Call ' tms_inst_tt00003 '. ' Mmmm ' ();

Roll back success

Set autocommit =0;delimiter $ $DROP PROCEDURE IF EXISTS  mmmm $$  CREATE definer= ' tms_admin ' @ '% ' PROCEDURE ' mmmm ' () BEGIN          DECLARE t_error INTEGER DEFAULT 0;    DECLARE CONTINUE HANDLER for sqlexception,sqlwarning,not FOUND  SET t_error=1;    SavePoint P1;              Update T_user Set instance_seq_id = ' tt00006 ';            Update T_user Set instance_seq_id000 = ' tt00007 ';            IF t_error = 1 then                 ROLLBACK to P1;            ELSE                 COMMIT;             END IF; end$ $DELIMITER;

Roll back success

The difference between set autocommit=0 and start transaction in MySQL