How to average 3 values in Sql Server?

Question

Hi folks,

I have three variables :-

@ScoreA DECIMAL(10,7)
@ScoreB DECIMAL(10,7)
@ScoreC DECIMAL(10,7)
@FinalScore DECIMAL(10, 7)

I wish to get the average of the three scores. BUT 1, 2 or all 3 values might be zero.

Eg. scenarios:

• A = 1.4, B=3.5, C=5.0; FinalScore = 3.3
• A = 0.0, B=0.0, C=0.0; FinalScore = 0.0
• A = 1.1, B=0.0, C=0.0; FinalScore = 1.1
• A = 0.0, B=2.0, C=4.8; FinalScore = 3.4

Cheers!

Answer 1

IF @A > 0 OR @B > 0 OR @C > 0
    SELECT ((@A + @B + @C) / 
        (0 + 
        CASE WHEN @A = 0 THEN 0 ELSE 1 END + 
        CASE WHEN @B = 0 THEN 0 ELSE 1 END + 
        CASE WHEN @C = 0 THEN 0 ELSE 1 END ))
ELSE
    SELECT 0.0

EDIT

Modified query to now handle divide by zero scenario's.

EDIT2

Here is "the trick with the AVG(..) function" :) with Common Table Expression

WITH T(I) AS (SELECT @A UNION SELECT @B UNION SELECT @C)
SELECT AVG(I) FROM T
WHERE I > 0

Answer 2

SELECT ((@A + @B + @C) / 
        (CASE WHEN (@A = 0.0 AND @B = 0.0 AND @C = 0.0) THEN 1 ELSE 0 END 
        + CASE WHEN @A = 0 THEN 0 ELSE 1 END 
        + CASE WHEN @B = 0 THEN 0 ELSE 1 END  
        + CASE WHEN @C = 0 THEN 0 ELSE 1 END 
        )
      )

Answer 3

For me this is easier to read and understand:

DECLARE
    @ScoreA DECIMAL(10,7),
    @ScoreB DECIMAL(10,7),
    @ScoreC DECIMAL(10,7),
    @FinalScore DECIMAL(10, 7)

SET @ScoreA = 1.4
SET @ScoreB = 3.5
SET @ScoreC = 5.0

DECLARE 
    @AVG TABLE (value DECIMAL(10,7))

INSERT INTO @AVG
    SELECT @ScoreA WHERE @ScoreA > 0
    UNION
    SELECT @ScoreB WHERE @ScoreB > 0
    UNION
    SELECT @ScoreC WHERE @ScoreC > 0

SELECT COALESCE(AVG(value), 0) FROM @AVG