SQL - What a SELECT FOR UPDATE cursor represent.[ANSWER]SELECT......FROM......FOR......UPDATE[OF column-re

GeekInterview.com > Interview Questions > Oracle > SQL

Go To First | Previous Question | Next Question

SQL | Question 35 of 170

What a SELECT FOR UPDATE cursor represent.

[ANSWER

]SELECT......FROM......FOR......UPDATE[OF column-reference][NOWAIT] The processing done in a fetch loop modifies the rows that have been retrieved by the cursor.

A convenient way of modifying the rows is done by a method with two parts: the FOR UPDATE clause in the cursor declaration, WHERE CURRENT OF CLAUSE in an UPDATE or declaration statement.

Total Answers and Comments: 3

Last Update: February 06, 2008

Sponsored Links

Best Rated Answer

—

No best answer available. Please pick the good answer available or submit your answer.

February 17, 2006 13:14:17

RACHANA

RE: What a SELECT FOR UPDATE cursor represent.

SELECT FOR UPDATE - when using this clause rdbms automatically obtains exclusive row level locks on all rows indentified by select statements' result set. noone else can modify these row except you until you comit or rollback.

Where Current of clause gives access to recently fetched row/record of cursor.

Is this answer useful? Yes | No

August 17, 2007 09:13:59

syam sundar

RE: What a SELECT FOR UPDATE cursor represent.

SELECT FOR UPDATE is a clause in the cursors

When you use this within the cursor it will be lock all affected rows. Any one except you can not modify the rows until & unless commit or rollback

Is this answer useful? Yes | No

February 06, 2008 15:05:58

g_sidhu

Member Since: August 2007 Contribution: 122

RE: What a SELECT FOR UPDATE cursor represent.[ANSWER]SELECT......FROM......FOR......UPDATE[OF column-reference][NOWAIT] The processing done in a fetch loop modifies the rows that have been retrieved by the cursor. A convenient way of modifying the rows i

The SELECT ... FOR UPDATE statement identifies the rows that will be updated or deleted, then locks each row in the result set. This is useful when you want to base an update on the existing values in a row. In that case, you must make sure the row is not changed by another user before the update.

FOR UPDATE clause in the cursor query is used to lock the affected rows when the cursor is opened. Because the Oracle Server releases locks at the end of the transaction, you should not commit across fetches from an explicit cursor if FOR UPDATE is used.

Is this answer useful? Yes | No

Go To Top