sql

Question

what is a cursor?why cursor is needed?it's uses?plz explain me all about cursor.and also give example for it.

Akkiraju Ivaturi · Answer

A cursor is a programming logic mostly used in stored procedures to perform complex logic on a row by row basis. The select statement in a stored procedure only helps you to get all the results but will not keep in memory so that you can work on each row. A cursor can only work on one row at a time. You cannot do something like a batch updates or insertions using cursors. To use a cursor, we need to follow the steps: 1. Declare a cursor that defines a resultset 2. Open the cursor variable to establish the resultset. 3. Fetch the data into local variables as needed from cursor, one row at a time. 4. Perform operations on each row. 5. Close the cursor when the operation is completed i.e., all row have been completed. The following statements are needed to define cursors: DECLARE CURSOR OPEN FETCH CLOSE DEALLOCATE Example of the cursor: DECLARE @AccountID INT DECLARE @getAccountID CURSOR SET @getAccountID = CURSOR FOR SELECT Account_ID FROM Accounts OPEN @getAccountID FETCH NEXT FROM @getAccountID INTO @AccountID WHILE @@FETCH_STATUS = 0 BEGIN PRINT @AccountID FETCH NEXT FROM @getAccountID INTO @AccountID END CLOSE @getAccountID DEALLOCATE @getAccountID Let me know if you have any questions.

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