How to shorten SQL script - sql

Question

According to my code below, I was using cursor to get all information in WInstance table. However, my query may have a problem with performance due to cursor. Is there any way to use nested-select instead of cursor? Please share me your idea.
My business here is to get only 1 of the same ItemID, SequenceID, TaskStatus, ListID, WebID, SiteID.
Technically, there are lots of the same ItemID, SequenceID, TaskStatus, ListID, WebID, SiteID in the joining tables of WInstance and WProgress with AssignTask = 'Assign task'. Therefore, I used distinct and cursorto loop through to get only the top 1 with order by.
Here is my code:
CREATE PROCEDURE dbo.CustomTasksHistory
(
#Username NVARCHAR(255)
)
AS
DECLARE #TempTableStatus TABLE
(
ItemID INT ,
SequenceID INT ,
TaskStatus NVARCHAR(25) ,
ListID UNIQUEIDENTIFIER ,
WebID UNIQUEIDENTIFIER ,
SiteID UNIQUEIDENTIFIER
);
DECLARE #ItemID INT;
DECLARE #SequenceID INT;
DECLARE #ListID UNIQUEIDENTIFIER;
DECLARE #WebID UNIQUEIDENTIFIER;
DECLARE #SiteID UNIQUEIDENTIFIER;
DECLARE #AssignTask VARCHAR(25);
SET #AssignTask = 'Assign task';
-- Select final TaskStatus of each ItemID with its SequenceID --
DECLARE cursor_ItemID CURSOR FAST_FORWARD READ_ONLY FOR
SELECT DISTINCT
WI.ItemID ,
WP.SequenceID ,
WI.ListID ,
WI.WebID ,
WI.SiteID
FROM dbo.WInstance WI
INNER JOIN dbo.WProgress WP ON WI.InstanceID = WP.InstanceID
WHERE WP.CurrentActivityTitle = #AssignTask;
OPEN cursor_ItemID;
FETCH NEXT FROM cursor_ItemID INTO #ItemID, #SequenceID, #ListID, #WebID, #SiteID;
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT INTO #TempTableStatus
( ItemID ,
SequenceID ,
TaskStatus ,
ListID ,
WebID ,
SiteID
)
SELECT TOP 1
WI.ItemID ,
WP.SequenceID ,
CASE WHEN WP.ActivityComplete = 0
THEN 'Not Started'
ELSE 'Completed'
END AS 'TaskStatus' ,
WI.ListID ,
WI.WebID ,
WI.SiteID
FROM dbo.WInstance WI
INNER JOIN dbo.WProgress WP ON WI.InstanceID = WP.InstanceID
WHERE WP.CurrentActivityTitle = #AssignTask
AND WI.ItemID = #ItemID
AND WP.SequenceID = #SequenceID
AND WI.ListID = #ListID
AND WI.WebID = #WebID
AND WI.SiteID = #SiteID
ORDER BY TimeStamp DESC;
FETCH NEXT FROM cursor_ItemID INTO #ItemID, #SequenceID, #ListID, #WebID, #SiteID;
END;
CLOSE cursor_ItemID;
DEALLOCATE cursor_ItemID;
SELECT *
FROM #TempTableStatus;

Answer 1

You don't need to use cursor. Replace it with below query
SELECT ItemID, SequenceID, TaskStatus, ListID, WebID, SiteID
FROM
(
SELECT RN = ROW_NUMBER() OVER (PARTITION BY WP.CurrentActivityTitle,
WI.ItemID, WP.SequenceID,
WI.ListID, WI.WebID, WI.SiteID
ORDER BY TimeStamp DESC),
WI.ItemID ,
WP.SequenceID ,
CASE WHEN WP.ActivityComplete = 0
THEN 'Not Started'
ELSE 'Completed'
END AS 'TaskStatus' ,
WI.ListID ,
WI.WebID ,
WI.SiteID
FROM dbo.WInstance WI
INNER JOIN dbo.WProgress WP ON WI.InstanceID = WP.InstanceID
WHERE WP.CurrentActivityTitle = #AssignTask
) D
WHERE RN = 1;