Store a subquery in a variable or something - tsql

Question

I've this query below, my need is that I want to do the substraction between 2 columns: S and M&L.
The problem is that S and M&L are a subqueries ... I've tried to store those subqueries on a variable, but it's not working ...
SELECT
[STORE] = ET2.ET_LIBELLE ,
[SELLER] = GCL5.GCL_LIBELLE,
(SELECT
COUNT(DISTINCT GL_NUMERO)
FROM GCLIGNEARTDIM
LEFT OUTER JOIN ETABLISS ET4 ON GL_ETABLISSEMENT=ET4.ET_ETABLISSEMENT
LEFT OUTER JOIN COMMERCIAL GCL4 ON GL_REPRESENTANT=GCL4.GCL_COMMERCIAL
WHERE
AND ET4.ET_LIBELLE = ET2.ET_LIBELLE
AND GCL4.GCL_LIBELLE = GCL5.GCL_LIBELLE
AND GP_TOTALTTC < 200
) S,
(SELECT
COUNT(DISTINCT GL_NUMERO)
FROM GCLIGNEARTDIM
LEFT OUTER JOIN ETABLISS ET4 ON GL_ETABLISSEMENT=ET4.ET_ETABLISSEMENT
LEFT OUTER JOIN COMMERCIAL GCL4 ON GL_REPRESENTANT=GCL4.GCL_COMMERCIAL
WHERE
AND ET4.ET_LIBELLE = ET2.ET_LIBELLE
AND GCL4.GCL_LIBELLE = GCL5.GCL_LIBELLE
AND GP_TOTALTTC > 200
) 'M&L'
FROM GCLIGNEARTDIM
LEFT OUTER JOIN ETABLISS ET2 ON GL_ETABLISSEMENT=ET2.ET_ETABLISSEMENT
LEFT OUTER JOIN COMMERCIAL GCL5 ON GL_REPRESENTANT=GCL5.GCL_COMMERCIAL
WHERE
GL_DATEPIECE = '2019-02-28'
GROUP BY
ET2.ET_LIBELLE,
GCL5.GCL_LIBELLE

Answer 1

If you're using Microsoft SQL, then one way to do this would be to use a CTE. I don't have any test data, so I'm just reposting your query (there are issues with the WHERE clauses that need to be addressed):
WITH cteData AS
(
SELECT [STORE] = ET2.ET_LIBELLE
, [SELLER] = GCL5.GCL_LIBELLE
, (
SELECT COUNT(DISTINCT GL_NUMERO)
FROM GCLIGNEARTDIM
LEFT OUTER JOIN ETABLISS ET4 ON GL_ETABLISSEMENT=ET4.ET_ETABLISSEMENT
LEFT OUTER JOIN COMMERCIAL GCL4 ON GL_REPRESENTANT=GCL4.GCL_COMMERCIAL
WHERE ET4.ET_LIBELLE = ET2.ET_LIBELLE
AND GCL4.GCL_LIBELLE = GCL5.GCL_LIBELLE
AND GP_TOTALTTC < 200
) S
, (
SELECT COUNT(DISTINCT GL_NUMERO)
FROM GCLIGNEARTDIM
LEFT OUTER JOIN ETABLISS ET4 ON GL_ETABLISSEMENT=ET4.ET_ETABLISSEMENT
LEFT OUTER JOIN COMMERCIAL GCL4 ON GL_REPRESENTANT=GCL4.GCL_COMMERCIAL
WHERE ET4.ET_LIBELLE = ET2.ET_LIBELLE
AND GCL4.GCL_LIBELLE = GCL5.GCL_LIBELLE
AND GP_TOTALTTC > 200
) 'M&L'
FROM GCLIGNEARTDIM
LEFT OUTER JOIN ETABLISS ET2 ON GL_ETABLISSEMENT=ET2.ET_ETABLISSEMENT
LEFT OUTER JOIN COMMERCIAL GCL5 ON GL_REPRESENTANT=GCL5.GCL_COMMERCIAL
WHERE GL_DATEPIECE = '2019-02-28'
GROUP BY ET2.ET_LIBELLE, GCL5.GCL_LIBELLE
)
SELECT *
, ([S] - [M&L]) AS [S minus M&L]
FROM cteData