CODE EXAMPLE FOR SQL

sql select if two columns are equal

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