The reason is that te value of is NULL during the cursor declaration, and this NULL value is used in each OPEN statement, not the new value that was assigned just before openning the cursor. Now when you call this procedure it outputs empty values:
This assignment also will not have any affect on used in the cursor SET = 'White' is NULL, and this NULL value will be used in cursor DECLARE VARCHAR (70 ) ĭECLARE cur CURSOR LOCAL FOR SELECT name FROM colors WHERE name = This assignment will not have any affect on used in the cursor SET = 'Red' In any programming language, we use a loop like FOREACH, FOR, WHILE, DO WHILE to iterate through one item at a time, the cursor follows the same approach, hence it might be preferred because it follows the same logic as the looping mechanism in the programming language. Note that SQL Server gets values of variables during the cursor declaration, not during execution of OPEN cursor statement. This can be done using cursors in SQL Server. SQL Server does not support cursors with parameters, so you have to use variables or pass values explicitly. A more serious problem arises if you have another procedure that uses a cursor with the same name, but different definition. Note that only the DECLARE statement fails, the procedure continues its execution and opens the previously declared cursor. # Msg 16915, Level 16, State 1, Procedure sp_date, Line 4 # A cursor with the name 'cur' already exists. PRINT the DEALLOCATE statement, the second and any subsequent call to this procedure returns 'cursor already exists' error: Now let's see what happens if you convert this procedure to SQL Server and use CLOSE statement without DEALLOCATE statement:ĭECLARE cur CURSOR FOR SELECT GETDATE ( ) You can invoke this procedure multiple times, and it successfully declares, opens and closes the cursor each time: Output The latest fetch status of all cursors can be obtained from the DMV sys.dm_exec_cursors.Consider the following sample procedure that uses a cursor (do not pay attention to its logic, it is just to demonstate cursor declaration and operations): SELECT abs(CURSOR_STATUS('global','person')) AS 'isCursorClosed?' Its more than 20 000 pieces (records) stored in one single box (like a table in SQL server) with the measure 70x40x40cm.
SQL clients can use a server cursor to fetch results of a query one-at-a-time, or in batches of N-at-a-time, rather than by the usual all-at-a-time, firehose, default query result set.
It consists of a query execution and some runtime state, including a current position. SELECT CURSOR_STATUS('global','person') AS 'isReady?' A server cursor is a cursor managed by SQL Engine. This is a simple example read the all rows in the cursor variable. 1 = The FETCH statement failed or the row was beyond the result set or end of record. If you had posted your real problem, rather than the artificial one you. When control is returned from the called stored procedure, reflects the last FETCH executed in the stored procedure, not the FETCH statement executed before the stored procedure is called.įunction returns an integer value as given below. Even still, older versions of SQL Server had some useful tricks to avoid cursors. Because, the result is unpredictable.įor instance, a user executes a FETCH statement from one cursor, and then calls a stored procedure that opens and processes the results from another cursor.
This function is used to get the current fetch status of a latest opened cursor.This function is global function for all cursors in the application and it is non-deterministic.
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