Implementing IF Condition Within a T-SQL UPDATE Statement

Question

Using T-SQL, I would like to execute an UPDATE statement that will SET columns only if the corresponding variables are defined.

Here's a simple pseudo-tsql example of what I'm trying to accomplish:

--Declaring vars
@ID int,
@Name nvarchar(20),
@Password nvarchar(10)

--Run the update
UPDATE User
SET
IF LEN(@NAME) > 0
  Name = @Name,
IF LEN(@Password) > 0
  Password = @Password

From what I can tell by reading how IF conditions work in T-SQL, in order to accomplish the same result as the above pseudo code, I would have to create an UPDATE statement for every IF condition - which is what I'm trying to avoid having to do.

Is it possible to dynamically SET fields/columns based on a condition using only one UPDATE statement? - If so, how?

gbn · Accepted Answer · 2010-07-15 06:18:49Z

57

The CASE expression

UPDATE User
SET
    Name = CASE WHEN LEN(@NAME) > 0 THEN @Name ELSE Name END,
    Password = CASE WHEN LEN(@Password) > 0 THEN @Password ELSE Password END
WHERE
   ...

answered Jul 15, 2010 at 6:18

gbn

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Ahmad Ebrahimi · Accepted Answer · 2013-11-30 14:53:36Z

2

I think this will be useful:

Create PROCEDURE [dbo].[CodeUpdate] 
(
    @Id int, 
    @Name nVarChar(150)=null, 
    @IsActive bit =null, 
    @IsSystem bit=null
) AS 
BEGIN 
    UPDATE [dbo].[Code] SET 
        [Name] = CASE WHEN @Name is null THEN [Name] ELSE @Name END,
        [IsActive] = CASE WHEN @IsActive is null THEN [IsActive] ELSE @IsActive END,
        [IsSystem] = CASE WHEN @IsSystem is null THEN [IsSystem] ELSE @IsSystem END
    WHERE  ID = @Id
End

Do you like it? Enjoy.

answered Nov 30, 2013 at 14:53

Ahmad Ebrahimi

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