SQL SELECT si deux colonnes sont égales
SELECT ta.C1
,ta.C2
,ta.C3
,ta.C4
FROM [TableA] ta
WHERE (SELECT COUNT(*)
FROM [TableA] ta2
WHERE ta.C2=ta2.C2
AND ta.C3=ta2.C3
AND ta.C4=ta2.C4)>1
Fantastic Frog