Description

table-name
Identifies the table to be locked. The table-name must identify a base table that exists at the current server, but must not identify a catalog table or a global temporary table.
IN SHARE MODE
Prevents concurrent application processes from executing any but read-only operations on the table.

A shared lock (*SHRNUP) is acquired for the application process in which the statement is executed. Other application processes may also acquire a shared lock (*SHRNUP) and prevent this application process from executing any but read-only operations.

IN EXCLUSIVE MODE ALLOW READ
Prevents concurrent application processes from executing any but read-only operations on the table.

An exclusive allow read lock (*EXCLRD) is acquired for the application process in which the statement is executed. Other application processes may not acquire a shared lock (*SHRNUP) and cannot prevent this application process from executing updates, deletes, and inserts on the table.

IN EXCLUSIVE MODE
Prevents concurrent application processes from executing any operations at all on the table.

An exclusive lock (*EXCL) is acquired for the application process in which the statement is executed.