MySQL查询多行

Question

我有一个mySql表...非常简单（id，firstColumn，secondColumn） 我想查询谁在firstColumn中显示重复值，并在firstColumn中显示相同的值

如果我有类似的东西

1, 14, 1
2, 14, 2
3, 15, 1
4, 15, 2
5, 14, 2
6, 15, 1
7, 16, 1
8, 17, 1

我的查询显示重复值

5, 14, 2
6, 15, 1

由于

Answer 1

试试这个：

SELECT column1, column2, COUNT(*)
FROM tableNAME
GROUP BY column1, column2
HAVING COUNT(*) > 1

Answer 2

解决方案1：

SELECT DISTINCT
  t1.id,
  t1.firstColumn
FROM
  tablename t1
INNER JOIN
  tablename t2
ON
  t1.firstColumn = t2.firstColumn

解决方案2：

SELECT
  id,
  firstColumn
FROM
  tablename
GROUP BY
  id, firstcolumn
HAVING
  COUNT(*) > 1