Hier ist das Beispiel mit Cursor:
DECLARE @VisitorID int
DECLARE @FirstName varchar(30), @LastName varchar(30)
-- declare cursor called ActiveVisitorCursor
DECLARE ActiveVisitorCursor Cursor FOR
SELECT VisitorID, FirstName, LastName
FROM Visitors
WHERE Active = 1
-- Open the cursor
OPEN ActiveVisitorCursor
-- Fetch the first row of the cursor and assign its values into variables
FETCH NEXT FROM ActiveVisitorCursor INTO @VisitorID, @FirstName, @LastName
-- perform action whilst a row was found
WHILE @@FETCH_STATUS = 0
BEGIN
Exec MyCallingStoredProc @VisitorID, @Forename, @Surname
-- get next row of cursor
FETCH NEXT FROM ActiveVisitorCursor INTO @VisitorID, @FirstName, @LastName
END
-- Close the cursor to release locks
CLOSE ActiveVisitorCursor
-- Free memory used by cursor
DEALLOCATE ActiveVisitorCursor
Hier ist nun das Beispiel, wie wir dasselbe Ergebnis erhalten können, ohne den Cursor zu verwenden:
/* Here is alternative approach */
-- Create a temporary table, note the IDENTITY
-- column that will be used to loop through
-- the rows of this table
CREATE TABLE #ActiveVisitors (
RowID int IDENTITY(1, 1),
VisitorID int,
FirstName varchar(30),
LastName varchar(30)
)
DECLARE @NumberRecords int, @RowCounter int
DECLARE @VisitorID int, @FirstName varchar(30), @LastName varchar(30)
-- Insert the resultset we want to loop through
-- into the temporary table
INSERT INTO #ActiveVisitors (VisitorID, FirstName, LastName)
SELECT VisitorID, FirstName, LastName
FROM Visitors
WHERE Active = 1
-- Get the number of records in the temporary table
SET @NumberRecords = @@RowCount
--You can use: SET @NumberRecords = SELECT COUNT(*) FROM #ActiveVisitors
SET @RowCounter = 1
-- loop through all records in the temporary table
-- using the WHILE loop construct
WHILE @RowCounter <= @NumberRecords
BEGIN
SELECT @VisitorID = VisitorID, @FirstName = FirstName, @LastName = LastName
FROM #ActiveVisitors
WHERE RowID = @RowCounter
EXEC MyCallingStoredProc @VisitorID, @FirstName, @LastName
SET @RowCounter = @RowCounter + 1
END
-- drop the temporary table
DROP TABLE #ActiveVisitors
