SQL Stored Procedure Get Distinct and Update

Question

The idea is to show how many times a user (by EmployeeID) is in the TblTableList and then update the TblTableStatusCount

I have been learning Fetch this week so wanted to ensure I have gone down the right path and this is a small database, can/should I use this for any size?

Code:

USE [database] 
        GO

        SET ANSI_NULLS ON
        GO
        SET QUOTED_IDENTIFIER ON
        GO
        Alter PROCEDURE [dbo].[spSummary]
            -- Add the parameters for the stored procedure here

        AS

        BEGIN

        DECLARE @StatusTotal AS Int
        DECLARE @Status0 AS Int
        DECLARE @Status1 AS Int
        DECLARE @Status2 AS Int
        DECLARE @Status3 AS Int

        --Cursor to loop through
        DECLARE @EmployeeID  AS NvarChar(10);
        DECLARE propCurs CURSOR FOR
        SELECT  EmployeeID FROM [TblTableList]

        --Open Loop Code
        OPEN propCurs;
        FETCH NEXT FROM propCurs INTO @EmployeeID
        WHILE @@FETCH_STATUS = 0  
        --Now do repeated code

          BEGIN

         --   SELECT @StatusTotal = COUNT(ID) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID  
            --SELECT @Status0 =  COUNT(DISTINCT(ID)) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID AND CurrentAlertStatus = '0'
            --SELECT @Status1 =  COUNT(DISTINCT(ID)) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID AND CurrentAlertStatus = '1'
            --SELECT @Status2 =  COUNT(DISTINCT(ID)) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID AND CurrentAlertStatus = '2'
            --SELECT @Status3 =  COUNT(DISTINCT(ID)) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID AND CurrentAlertStatus = '3'

        with cnt as ( 
           SELECT 
             1 as cntAll 
             , case WHEN CurrentAlertStatus = '0' then 1 else 0  end as cnt1
             , case WHEN CurrentAlertStatus = '1' then 1 else 0  end as cnt2
             , case WHEN CurrentAlertStatus = '2' then 1 else 0  end as cnt3
              , case WHEN CurrentAlertStatus = '3' then 1 else 0  end as cnt4
           from [TblTableCountFrom] where EmployeeID = @EmployeeID
        )
        SELECT @StatusTotal = sum(cntAll),  
          @Status0  = sum(cnt1),
          @Status1  = sum(cnt2),
          @Status2  = sum(cnt3),
          @Status3  = sum(cnt4)
          FROM cnt;
            -- Check if ID Exists

            --HERE NEED TO CHECK IF EXISTS OR SHOULD I WIPE THE TABLE AT THE START? 
            IF EXISTS (SELECT EmployeeID FROM [TblTableCount] WHERE @EmployeeID = EmployeeID)

                UPDATE [TblTableCountFrom]Count 
                SET StatusTotalCount = @StatusTotal, Status0 = @Status0, Status1 = @Status1, Status2 = @Status2, Status3 = @Status3
                WHERE EmployeeID = @EmployeeID
              Else
                INSERT INTO [TblTableCount] 
                (EmployeeID, StatusTotalCount, Status0, Status1 , Status2, Status3) VALUES (@EmployeeID, @StatusTotal,@Status0, @Status1, @Status2,@Status3 )

            END

            -- Now we bookend the loop code

            FETCH NEXT FROM propCurs INTO @EmployeeID

        END

        --Tidy up and close loop code
        CLOSE propCurs;
        DEALLOCATE propCurs;

Answer 1

Consistency

You have this:

    with cnt as ( 
       SELECT 
         1 as cntAll 
         , case WHEN CurrentAlertStatus = '0' then 1 else 0  end as cnt1
         , case WHEN CurrentAlertStatus = '1' then 1 else 0  end as cnt2
         , case WHEN CurrentAlertStatus = '2' then 1 else 0  end as cnt3
         , case WHEN CurrentAlertStatus = '3' then 1 else 0  end as cnt4
       from [TblTableCountFrom] where EmployeeID = @EmployeeID

And this:

    SELECT @StatusTotal = sum(cntAll),  
      @Status0  = sum(cnt1),
      @Status1  = sum(cnt2),
      @Status2  = sum(cnt3),
      @Status3  = sum(cnt4)
      FROM cnt;

While both styles of formatting are perfectly acceptable, it's better to sick with the same throughout your code for readability.

Same for this:

    DECLARE @StatusTotal AS Int

And this:

    DECLARE @EmployeeID  AS NvarChar(10);

It works with or without a semicolon in this case, try to stick to one method.

The elephant in the room

Cursors are very slow. Especially using a bunch of variables with it. I understand you were experimenting with a function of SQL you are new to, and that's great. We all do that, play with our shiny new toy.

However, for something that's production and that will get called regularly, efficiency is key. Your clients won't care how cool your code looks, especially if it takes longer to run.

It is very rare that you actually need a cursor. Think about it this way. If you have 100 employees in your table, then it is running the query 100 times instead of once. Imagine 5000 or 50000 employees how long this would take.

I commented out all sections I think you could safely dispense with for better efficiency:

    USE [database] 
    GO
    SET ANSI_NULLS ON
    GO
    SET QUOTED_IDENTIFIER ON
    GO
    Alter PROCEDURE [dbo].[spSummary]
        -- Add the parameters for the stored procedure here
    AS
    BEGIN

    DECLARE @StatusTotal AS Int
    DECLARE @Status0 AS Int
    DECLARE @Status1 AS Int
    DECLARE @Status2 AS Int
    DECLARE @Status3 AS Int

    --Cursor to loop through
    DECLARE @EmployeeID  AS NvarChar(10);


    /* DECLARE propCurs CURSOR FOR
    SELECT  EmployeeID FROM [TblTableList]

    --Open Loop Code
    OPEN propCurs;
    FETCH NEXT FROM propCurs INTO @EmployeeID
    WHILE @@FETCH_STATUS = 0  
    --Now do repeated code

      BEGIN */

     -- SELECT @StatusTotal = COUNT(ID) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID  
     -- SELECT @Status0 =  COUNT(DISTINCT(ID)) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID AND CurrentAlertStatus = '0'
     -- SELECT @Status1 =  COUNT(DISTINCT(ID)) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID AND CurrentAlertStatus = '1'
     -- SELECT @Status2 =  COUNT(DISTINCT(ID)) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID AND CurrentAlertStatus = '2'
     -- SELECT @Status3 =  COUNT(DISTINCT(ID)) FROM [TblTableCountFrom] WHERE EmployeeID = @EmployeeID AND CurrentAlertStatus = '3'

    with cnt as ( 
       SELECT 
         1 as cntAll 
         , case WHEN CurrentAlertStatus = '0' then 1 else 0  end as cnt1
         , case WHEN CurrentAlertStatus = '1' then 1 else 0  end as cnt2
         , case WHEN CurrentAlertStatus = '2' then 1 else 0  end as cnt3
         , case WHEN CurrentAlertStatus = '3' then 1 else 0  end as cnt4
       from [TblTableCountFrom] where EmployeeID = @EmployeeID
    )
    SELECT @StatusTotal = sum(cntAll),  
      @Status0  = sum(cnt1),
      @Status1  = sum(cnt2),
      @Status2  = sum(cnt3),
      @Status3  = sum(cnt4)
      FROM cnt;
        -- Check if ID Exists

        --HERE NEED TO CHECK IF EXISTS OR SHOULD I WIPE THE TABLE AT THE START? 
        IF EXISTS (SELECT EmployeeID FROM [TblTableCount] WHERE @EmployeeID = EmployeeID)

            UPDATE [TblTableCountFrom]Count 
            SET StatusTotalCount = @StatusTotal, Status0 = @Status0, Status1 = @Status1, Status2 = @Status2, Status3 = @Status3
            WHERE EmployeeID = @EmployeeID
          Else
            INSERT INTO [TblTableCount] 
            (EmployeeID, StatusTotalCount, Status0, Status1 , Status2, Status3) VALUES (@EmployeeID, @StatusTotal,@Status0, @Status1, @Status2,@Status3 )

        /* END

        -- Now we bookend the loop code

        FETCH NEXT FROM propCurs INTO @EmployeeID */

    END

    --Tidy up and close loop code
    /* CLOSE propCurs;
    DEALLOCATE propCurs; */

Also!

Do what @ckuhn203 said about a view.

Answer 2

Nitpicks

• The keyword capitalization is inconsistent. Alter PROCEDURE should be ALTER PROCEDURE. Likewise with case WHEN ... then 1 else 0 end as cntX. Keywords should be capitalized to distinguish them from variables and fields. They should at least be consistent.
• @Status0 through @Status3 are pretty bad variable names. I have no idea what the difference between the different statuses is, so I can't offer anything better unfortunately.

Not so nit-picky

• I have serious concerns about storing counts statically in a table. What happens if I add a new record? When I query the count from the field, it will lie to me. It's better to calculate the count when you actually need it. It's preferable to create a view to return this kind of data. If you absolutely insist that the count be stored in a table, an update trigger would be more appropriate.
• Generally speaking, cursors are to be avoided. Set based approaches are always better in sql.

The code in question actually looks pretty good beyond the nit-picky stuff. It's just probably not the best approach to take.

Answer 3

Before I even got to your code I found 2 tables that were named so badly it made me want to stop reading and post an answer.

TblTableList

TblTableStatusCount

Then I glanced at the code and found another

TblTableCount

please tell me that these are not the names of permanent tables in your Database!!!

bad hungarian notation with pascal casing that should be camel casing. ugh!

TblTableCount that is really redundant.

I don't know what these are being used for but I am sure you can think of better names than these.

---

Don't try to make your variable/table names shorter in code, EVER, it makes the code more obscure than it has to be and saving the time typing out the code now could mean ripping hair out later because you don't remember what your code is doing.