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LOCK TABLE
LOCK TABLE
Syntax
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Authorization
Must have DBA privilege, ownership of the table, INSERT privilege on the table, or SELECT
privilege on all the tables or views referred to in the query_expression, if a
query_expression is specified.
Related statements
REVOKE
Explicitly locks one or more specified tables for shared or exclusive access.
LOCK TABLE table_name [ , table_name ] , ...
IN { SHARE | EXCLUSIVE } MODE ;
table_name
The table in the database that you want to lock explicitly. You can specify one table or a
comma-separated list of tables.
SHARE MODE
Allows all transactions to read the tables. Prohibits all other transactions from modifying
the tables. After you acquire an explicit lock on a table in SHARE MODE, any SELECT
statements in your transaction can read rows and do not implicitly acquire individual
record locks. Any INSERT, UPDATE, and DELETE statements do acquire record locks.
EXCLUSIVE MODE
Allows the current transaction to read and modify the tables, and prohibits any other
transactions from reading or modifying the tables. After you acquire an explicit lock on a
table in EXCLUSIVE MODE, you can SELECT, INSERT, UPDATE, and DELETE rows, and your
transaction does not implicitly acquire individual record locks for these operations.
Examples Unless another transaction holds an EXCLUSIVE lock on the teratab and megatab tables, the
SHARE MODE example explicitly locks the tables. The shared lock allows all transactions to read
the tables. Only the current transaction can modify the tables, as shown in the following
example:
LOCK TABLE teratab, megatab IN SHARE MODE ;
Unless another transaction holds a lock on the teratab table, the EXCLUSIVE MODE example
locks the teratab table for exclusive use by the current transaction. No other transactions can
read or modify the teratab table, as shown in the following example:
LOCK TABLE teratab IN EXCLUSIVE MODE ;