START TRANSACTION
Function
START TRANSACTION starts a transaction. If the isolation level, read/write mode, or deferrable mode is specified, a new transaction will have those characteristics. You can also specify them using SET TRANSACTION.
Precautions
None
Syntax
Format 1: START TRANSACTION
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START TRANSACTION [ { ISOLATION LEVEL { READ COMMITTED | READ UNCOMMITTED | SERIALIZABLE | REPEATABLE READ } | { READ WRITE | READ ONLY } } [, ...] ]; |
Format 2: BEGIN
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BEGIN [ WORK | TRANSACTION ] [ { ISOLATION LEVEL { READ COMMITTED | READ UNCOMMITTED | SERIALIZABLE | REPEATABLE READ } | { READ WRITE | READ ONLY } } [, ...] ]; |
Parameter Description
Parameter |
Description |
Value Range |
---|---|---|
WORK | TRANSACTIO |
Optional keyword in the BEGIN format, which does not affect the operation. |
- |
ISOLATION LEVEL |
Transaction isolation level. This parameter determines the data that a transaction can view if other concurrent transactions exist.
NOTE:
The isolation level of a transaction cannot be reset after the first clause (INSERT, DELETE, UPDATE, FETCH, COPY) for modifying data is executed in the transaction. |
|
READ WRITE | READ ONLY |
Transaction access mode. |
Read-write mode or read-only mode. |
Examples
- Start a transaction in default mode.
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START TRANSACTION; SELECT * FROM tpcds.reason; END;
- Start a transaction with the isolation level being READ COMMITTED and the access mode being READ WRITE:
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START TRANSACTION ISOLATION LEVEL READ COMMITTED READ WRITE; SELECT * FROM tpcds.reason; COMMIT;
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