nsactional tables.

in_transaction
--------------

The in_transaction system variable is a session-only, read-only variable that
returns 1 inside a transaction, and 0 if not in a transaction.

WITH CONSISTENT SNAPSHOT
------------------------

The WITH CONSISTENT SNAPSHOT option starts a consistent read for storage
engines such as InnoDB that can do so, the same as if a START TRANSACTION
followed by a SELECT from any InnoDB table was issued.

See Enhancements for START TRANSACTION WITH CONSISTENT SNAPSHOT.

Examples
--------

START TRANSACTION;
SELECT @A:=SUM(salary) FROM table1 WHERE type=1;
UPDATE table2 SET summary=@A WHERE type=1;
COMMIT;

URL: https://mariadb.com/kb/en/start-transaction/https://mariadb.com/kb/en/start-transaction/