Question

我的查询显示如下数据：

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

但我想显示这样的数据：

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

基本上在重复数据上我想显示一个空单元格。它可以吗？这是我原来的疑问：

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;

我该如何更改查询？提前谢谢。

Answer 1

对于mysql，您可以使用变量和CASE来检查值是新的还是重复的

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

Fiddle Demo

Answer 2

对于Oracle风味：

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

SqlFiddle

我该如何更改查询？

2 个答案:

Fiddle Demo