MSSQL How do I get average of four records from different tables? - sql

Question

I have four tables and I need to find the average of each score for a particular id. I do not need the ENTIRE Column average, but the average of each record with the same id in each table.
I have tried this:
SELECT DISTINCT M.system_id, S.name, SUM(A.Score + WAL.score + F.score + WIN.score) / 4
AS avgScore
FROM dbo.T3_MovementSystemJoin AS M
INNER JOIN dbo.T3_systems AS S ON M.system_id = S.id
INNER JOIN T3_ApplicationSystemJoin AS A ON A.Application_id = #application_id
INNER JOIN T3_WallTypeSystemJoin AS WAL ON WAL.wall_id = #wall_id
INNER JOIN T3_FenestrationSystemJoin AS F ON F.fenestration_id = #fen_id
INNER JOIN T3_WindowOrientation_System AS WIN ON WIN.window_id = #window_id
INNER JOIN T3_ConstructionSystemJoin AS C ON C.contruction_id = #construction_id
INNER JOIN T3_JointDepthSystemJoin AS J ON J.JointDepth_id = #JointDepth_id
INNER JOIN T3_JointGapSystemJoin AS JG ON JG.JointGap_id = #JointGap_id
WHERE (M.movement_id = #movement_id)
GROUP BY M.System_id, S.name
:
Thanks for your help!

Answer 1

No Sum needed (and no grouping too)
SELECT DISTINCT M.system_id, S.name, (IsNull(A.Score, 0) + IsNull(WAL.score, 0) + IsNull(F.score, 0) + IsNull(WIN.score, 0)) /4
as avgscore
FROM dbo.T3_MovementSystemJoin AS M
INNER JOIN dbo.T3_systems AS S ON M.system_id = S.id
INNER JOIN T3_ApplicationSystemJoin AS A ON A.Application_id = #application_id
INNER JOIN T3_WallTypeSystemJoin AS WAL ON WAL.wall_id = #wall_id
INNER JOIN T3_FenestrationSystemJoin AS F ON F.fenestration_id = #fen_id
INNER JOIN T3_WindowOrientation_System AS WIN ON WIN.window_id = #window_id
INNER JOIN T3_ConstructionSystemJoin AS C ON C.contruction_id = #construction_id
INNER JOIN T3_JointDepthSystemJoin AS J ON J.JointDepth_id = #JointDepth_id
INNER JOIN T3_JointGapSystemJoin AS JG ON JG.JointGap_id = #JointGap_id
WHERE (M.movement_id = #movement_id)

Answer 2

SELECT DISTINCT M.system_id
,S.name
,(ISNULL(A.Score,0) + ISNULL(WAL.score,0) + ISNULL(F.score,0) + ISNULL(WIN.score,0)) /4 as 'AvgScore'
FROM dbo.T3_MovementSystemJoin AS M
INNER JOIN dbo.T3_systems AS S ON M.system_id = S.id
INNER JOIN T3_ApplicationSystemJoin AS A ON A.Application_id = #application_id
INNER JOIN T3_WallTypeSystemJoin AS WAL ON WAL.wall_id = #wall_id
INNER JOIN T3_FenestrationSystemJoin AS F ON F.fenestration_id = #fen_id
INNER JOIN T3_WindowOrientation_System AS WIN ON WIN.window_id = #window_id
INNER JOIN T3_ConstructionSystemJoin AS C ON C.contruction_id = #construction_id
INNER JOIN T3_JointDepthSystemJoin AS J ON J.JointDepth_id = #JointDepth_id
INNER JOIN T3_JointGapSystemJoin AS JG ON JG.JointGap_id = #JointGap_id
WHERE (M.movement_id = #movement_id)

Answer 3

If you don't want NULL values to become zeros and included in the average:
SELECT DISTINCT M.system_id, S.name, X.avgScore
FROM dbo.T3_MovementSystemJoin AS M
INNER JOIN dbo.T3_systems AS S ON M.system_id = S.id
INNER JOIN T3_ApplicationSystemJoin AS A ON A.Application_id = #application_id
INNER JOIN T3_WallTypeSystemJoin AS WAL ON WAL.wall_id = #wall_id
INNER JOIN T3_FenestrationSystemJoin AS F ON F.fenestration_id = #fen_id
INNER JOIN T3_WindowOrientation_System AS WIN ON WIN.window_id = #window_id
INNER JOIN T3_ConstructionSystemJoin AS C ON C.contruction_id = #construction_id
INNER JOIN T3_JointDepthSystemJoin AS J ON J.JointDepth_id = #JointDepth_id
INNER JOIN T3_JointGapSystemJoin AS JG ON JG.JointGap_id = #JointGap_id
CROSS APPLY ( SELECT AVG(s) FROM (VALUES (A.Score),(WAL.score),(F.score),(WIN.score) ) scores(s) ) X(avgScore)
WHERE (M.movement_id = #movement_id)
GROUP BY M.System_id, S.name