CODEWITHSUNDEEP
sqlsql-servert-sql
t-sql_Cliff
t-sql_Cliff

Reputation: 23

T-sql: Cannot see why IF clause never gets called

I have a table like this:

    CREATE TABLE [dbo].[Scores](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [Score] [float] NULL,
 CONSTRAINT [PK_Scores] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

And I have some INSERTs

INSERT INTO Scores (Score) VALUES ( 0.5)
INSERT INTO Scores (Score) VALUES ( 2)
INSERT INTO Scores (Score) VALUES ( 3)
INSERT INTO Scores (Score) VALUES ( 4.5)

Then I realize that I need to change all scores where 0.5 should be 2 etc. So, I use a cursor to help me with that. Like this: 

DECLARE @id int  
DECLARE @score float
DECLARE myCursor CURSOR LOCAL FAST_FORWARD FOR     

SELECT Id, Score      
FROM [dbo].[Scores]
OPEN myCursor FETCH NEXT FROM myCursor INTO @id, @score 
WHILE @@FETCH_STATUS = 0 
BEGIN     
    PRINT 'Id: ' PRINT @id    
    PRINT 'Score: ' PRINT @score       
    -- do your tasks here      
    FETCH NEXT FROM myCursor INTO @id, @score

    IF @score = 2 
    BEGIN 
        UPDATE Scores set Score = 3.0 WHERE Id = @id
    END
    IF @score = 3 
    BEGIN 
        UPDATE Scores set Score = 4.0 WHERE Id = @id
    END
    IF @score = 0.5
    BEGIN 
        UPDATE Scores set Score = 2.0 WHERE Id = @id
    END
    IF @score = 4.5
    BEGIN
        UPDATE Scores set Score = 5.0 WHERE Id = @id
    END
END  
CLOSE myCursor DEALLOCATE myCursor

Before you propose a nicer solution, please tell me why this row never gets called:

UPDATE Scores set Score = 2.0 WHERE Id = @id

Upvotes: 2

Views: 99

Answers (2)

DaveShaw
DaveShaw

Reputation: 52788

Update Scores
Set Score = 
  case 
    when Score = 0.5 then 2
    when Score = 4.5 then 5
    --etc...
    else Score
  end;

Edit: Sorry, missed the point of it.

Answer is because the fetches are wrong. Put the 

FETCH NEXT FROM myCursor INTO @id, @score

At the bottom of the cursor loop. You are fetching row 1 once outside the loop and once again at the top (but after printing out the values).

Upvotes: 4

Andrew
Andrew

Reputation: 14447

Rounding error is a possibility. What happens if you try declaring Score as a decimal column (and variable) rather than as a float?

Upvotes: 0

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