2.3.74 SET TRANSACTION

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2 The SQL Language : 2.3 SQL Commands : 2.3.74 SET TRANSACTION

SET TRANSACTION -- set the characteristics of the current transaction
SET TRANSACTION transaction_mode
where transaction_mode is one of:
The SET TRANSACTION command sets the characteristics of the current transaction. It has no effect on any subsequent transactions. The available transaction characteristics are the transaction isolation level and the transaction access mode (read/write or read-only). The isolation level of a transaction determines what data the transaction can see when other transactions are running concurrently:
The transaction isolation level cannot be changed after the first query or data-modification statement (SELECT, INSERT, DELETE, UPDATE, or FETCH) of a transaction has been executed. The transaction access mode determines whether the transaction is read/write or read-only. Read/write is the default.
When a transaction is read-only, the following SQL commands are disallowed: INSERT, UPDATE, and DELETE if the table they would write to is not a temporary table; all CREATE, ALTER, and DROP commands; COMMENT, GRANT, REVOKE, TRUNCATE; and EXECUTE if the command it would execute is among those listed. This is a high-level notion of read-only that does not prevent all writes to disk.

2 The SQL Language : 2.3 SQL Commands : 2.3.74 SET TRANSACTION

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