columnA columnB
1         a
1         b
1         c
2         a
2         x
3         z
3         w

columnA columnB
1         a
          b
          c
2         a
          x
3         z
          w

SELECT t1.columnnA, t2.columnB
FROM table1 t1
INNER JOIN table2 t2 ON t1.id = t2.id
GROUP BY t1.columnnA, t2.columnB
ORDER BY t1.columnnA, t2.columnB;

SELECT (CASE WHEN rnum = 1 THEN v1.A ELSE NULL END) A, B
  FROM (  SELECT t1.columnA A,
                 t2.columnB B,
                 ROW_NUMBER () OVER (PARTITION BY t1.id ORDER BY t1.columnA)
                    rnum
            FROM t1 INNER JOIN t2 ON (t1.id = t2.id)
        ORDER BY t1.columnA, t2.columnB) v1

SELECT
CASE WHEN @check != columnA THEN columnA END refcolumnA,
columnB,
@check:=columnA
FROM Table1
,(SELECT @check:=0) t
ORDER BY columnA