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In SQL Server 2000, you can return an output parameter with theCURSOR data type, which can be further manipulated by the calling routine. The CURSOR_STATUS function can be used effectively with stored proceduresthat call another procedure, which returns an output parameter with the CURSORdata type. Results: - cursor has 0 rows- cursor has 2 rows- Ringer Albert- Ringer Anne- cursor has 0 rows CURSOR_STATUS The following example shows you how the valuechanges during the lifetime of the cursor: SET NOCOUNT ON DECLARE VARCHAR(20), VARCHAR(20)DECLARE my_cursor CURSOR STATIC FORSELECT au_lname, au_fname FROM authors WHERE au_lname = 'ringer'SELECT 'cursor has ' + AS VARCHAR) + ' rows'OPEN my_cursorFETCH NEXT FROM my_cursor INTO 'cursor has ' + AS VARCHAR) + ' rows'WHILE = 0BEGIN SELECT FETCH NEXT FROM my_cursor INTO my_cursorSELECT 'cursor has ' + AS VARCHAR) + ' rows'DEALLOCATE my_cursor DYNAMICcursors always return ≡ as value of can mean one of the following: Therefore, the number of rows can changedue to the addition or deletion of rows in the underlying tables. The cursor is DYNAMIC in other words, it reflects thechanges to the data within the cursor. "m" is the value of records in the keyset. Please refer to theSQL Server online documentation for more information on asynchronous populationof cursors. This means that if you have three cursorsopen, will return the number of rows in the third can take the following valueĬursor is being populated asynchronously. Results: - Ringer Albert- fetch status is 0- Ringer Anne- fetch status is -1 function returns the number of rows in the cursor that wasopened last on the current connection. Once we get to the end of the result set, ≡: SET NOCOUNT ON DECLARE VARCHAR(20), VARCHAR(20)DECLARE my_cursor CURSOR STATIC FORSELECT au_lname, au_fname FROM authors WHERE au_lname = 'ringer'OPEN my_cursorFETCH NEXT FROM my_cursor INTO = 0BEGIN SELECT FETCH NEXT FROM my_cursor INTO SELECT 'fetch status is ' + AS VARCHAR)ENDCLOSE my_cursorDEALLOCATE my_cursor Although the cursor fetches rows successfully, is 0. The fetched row is missing, which means that the recordyou're trying to fetch has been deleted or its key has been updated sinceyou opened the cursor.įor example, the following cursor returns the names of authorswith the last name of Ringer. Forinstance, if you attempt to grab the one-hundredth record within a cursor thathas 40 records, the FETCH status will be ≡.
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Alternatively, thiscan also mean that we attempted grabbing a record that does not exist. Please refer to the SQL Server onlinedocumentation for more information about the syntax of FETCH [NEXT, PRIOR,ABSOLUTE, can take one of the following three ValueĪ successful fetch of a row within a cursorįETCH has failed, which can mean that we're at thebeginning (or end) or the set of records within the cursor. You can use FETCH to move to the previous rowor to a particular row within the cursor. Note: Typically, the FETCH command is used to move to the next row,but that is not always the case. most commonly used cursor function is This functiondetermines whether FETCH keyword has successfully moved to a row within thecursor. If you don't know much about cursors or if you need a refresher, pleaserefer to the SQL Server online documentation for details. At this point, the cursorrepresentation is destroyed and the cursor cannot be resurrected. However, youcan reopen the cursor with the OPEN keyword and perform additional work with thecursor.įinally, the cursor is DEALLOCATED. At this point, you can't populate the cursorwith additional rows, nor can you work with rows within the cursor. The cursor is populated by using the FETCH keyword.Ī WHILE loop is executed within the cursor to do some work with the rowsin the cursor, with the condition that FETCH command is successful. (However, the cursor doesn't have any data yet.) The cursor is OPENEDat this point, you can start populating thecursor with rows. The cursor is declared using the DECLARE CURSOR statementthissimply creates a cursor within SQL Server memory. Although there is not room to go into adetailed discussion of cursors, the typical cursor life cycle is as follows: In order to understand how cursor functions work, you must first be familiarwith the cursor's life cycle. SQL Server supports three functions that can help you while working withcursors: and CURSOR_STATUS. Recall that cursors are one way to loop through records within a table (orseveral tables joined together) and perform a certain action on each affectedrecord. Microsoft SQL Server 2000 DBA Survival Guide, 2nd Edition