Question

I am struggling with a creating a query. It is related to a large and complicated database but for the sake of this post I have boiled the problem down to something simpler.

I have three tables X, Y, Z defined as

CREATE TABLE [dbo].[X](   [ID] [bigint] NOT NULL )  CREATE TABLE [dbo].[Y](   [ID] [nchar](10) NOT NULL )  CREATE TABLE [dbo].[Z](   [IDX] [bigint] NOT NULL,   [IDY] [nchar](10) NOT NULL ) 

They contain the following data

Table X    Table Y    Table Z ID         ID         IDX  IDY --         --         ---  --- 1          A          1    A          2          B          1    B          3          C          1    A 

I want to create a query that produces the following result

Count  IDX  IDY =====  ===  ===     2    1    A     1    1    B     0    1    C     0    2    A     0    2    B     0    2    C     0    3    A     0    3    B     0    3    C 

My initial thought was

SELECT COUNT(*), X.ID, Y.ID FROM   X   CROSS JOIN Y   FULL OUTER JOIN Z ON X.ID = Z.IDX AND Y.ID = Z.IDY GROUP BY X.ID, Y.ID 

but this turns out to be on the wrong road.

Any ideas?

Answer 1

SELECT     (SELECT COUNT(*) FROM Z WHERE IDX = X.ID AND IDY = Y.ID),     X.ID,     Y.ID FROM     X,Y 

That’s your answer… why do you possibly want that query, no clue 🙂