SQL in a Nutshell

Name

START TRANSACTION

Synopsis

New in SQL99, the START TRANSACTION statement allows all the functions of SET TRANSACTION to be performed and allows a new transaction to be initiated.

Vendor	Command
SQL Server	Not supported; see BEGIN TRAN later
MySQL	Not supported
Oracle	Not supported
PostgreSQL	Not supported; see BEGIN TRAN later

SQL99 Syntax and Description

START TRANSACTION { {READ ONLY | READ WRITE}[,...]
| ISOLATION LEVEL 
  {READ COMMITTED 
  | READ UNCOMMITTED 
  | REPEATABLE READ
  | SERIALIZABLE}[,...]
| DIAGNOSTIC SIZE INT};

The only difference between SET and START is that SET is considered outside of the current transaction, while START is considered the marking of a new transaction.

BEGIN TRANSACTION

The command BEGIN TRANSACTION provides similar functionality to START TRANSACTION. Both Microsoft SQL Server and PostgreSQL support BEGIN TRANSACTION, though they have slight variations in their syntax. Oracle supports implicit, but not explicit, transactions. MySQL doesn’t support atomic transactions at all. BEGIN TRANSACTION declares an explicit transaction, but it does not set isolation levels.

The Microsoft SQL Server syntax is:

BEGIN TRAN[SACTION] [transaction_name | @transaction_variable
[WITH MARK [ 'log_description' ] ] ]

Microsoft SQL Server allows a name to be assigned to a transaction or to reference transactions using a variable. It does not affect or add to functionality. When nesting transactions, only the outermost BEGIN . . . COMMIT or BEGIN . . . ROLLBACK ...