Oracle SELECT FOR UPDATE operator.

Preamble

The SELECT FOR UPDATE command allows you to lock entries in the resulting cursor set. The blocking of records is removed when the following commit or rollback commands are executed.

Syntax of SELECT FOR UPDATE operator

CURSOR_cursor name
IS
select_statement
FOR UPDATE [OF column_list] [NOWAIT];

Parameters and arguments of the operator

• cursor name – cursor name.
• select_statement – command SELECT, which will fill the resulting set of cursors.
• column_list – of columns in the cursor of the resulting set of cursors that you want to update.
• NOWAIT  – is optional. The cursor will not wait for resources.

For example, you could use the Oracle SELECT FOR UPDATE operator in the following way:

CURSOR c1
IS
SELECT course_number, instructor
FROM courses_tbl
FOR UPDATE OF instructor;

If you plan to update or delete records referred to by the SELECT FOR UPDATE operator, you can use the WHERE CURRENT OF operator.

Basics of Oracle SQL Select Update Alter Operators WildCard

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