This statement is an extension to the ANSI/ISO standard for SQL.
>>-UNLOCK TABLE--+-table---+----------------------------------->< '-synonym-'
| Element | Description | Restrictions | Syntax |
|---|---|---|---|
| synonym | Synonym for a table to unlock | The synonym and the table to which it points must exist | Database Object Name, p. Database Object Name |
| table | Table to unlock | Must be in a database without transactions and must be a table that you previously locked | Database Object Name, p. Database Object Name |
You can lock a table if you own the table or if you have the Select privilege on the table, either from a direct grant to yourself or from a grant to public. You can only unlock a table that you locked. You cannot unlock a table that another process locked. Only one lock can apply to a table at a time.
You must specify the name or synonym of the table that you are unlocking. Do not specify the name of a view, or a synonym for a view.
To change the lock mode of a table in a database without transactions, use the UNLOCK TABLE statement to unlock the table, then issue a new LOCK TABLE statement. The following example shows how to change the lock mode of a table in a database that was created without transactions:
LOCK TABLE items IN EXCLUSIVE MODE ... UNLOCK TABLE items ... LOCK TABLE items IN SHARE MODE
The UNLOCK TABLE statement fails if it is issued within a transaction. Table locks set within a transaction are released automatically when the transaction completes.
If you are using an ANSI-compliant database, do not issue an UNLOCK TABLE statement. The UNLOCK TABLE statement fails if it is issued within a transaction, and a transaction is always in effect in an ANSI-compliant database.
Related statements: BEGIN WORK, COMMIT WORK, LOCK TABLE, and ROLLBACK WORK
For a discussion of concurrency and locks, see the IBM Informix Guide to SQL: Tutorial.