In a database, at the same time two users might be accessing the similar data. E.g if one user is reading columnís value from database and other one is updating column at the same time. This is possible that 1st user may get old & update data, at the same time.
To prevent these situations, transactions are provided by DBMS so that to maintain data in persistent state. More than 1 user may access database with data concurrency, at the same time.
More than 1 SQL statements