Question

嗨，我试图计算相同值的行数，

id,value
1 | a
2 | b
3 | c
4 | d
5 | e

我的查询是

select value, count(*) as Count from mytable  where id in('4','2','4','1','4') group by value having count(*) > 1

我的预期输出，

value,Count
 d |  3
 b |  1
 a |  1

谢谢，任何帮助将不胜感激

Answer 1

试试：

  SELECT value, count(value) AS Count 
  FROM mytable m
    WHERE value = m.value
    GROUP BY value

Answer 2

SELECT t.id, t.value, COUNT(t.id) 
FROM 
  test t
  JOIN 
    ( SELECT 1 AS id
      UNION ALL SELECT 3
      UNION ALL SELECT 3
      UNION ALL SELECT 4
      UNION ALL SELECT 1
      UNION ALL SELECT 1 ) AS tmp
    ON t.id = tmp.id
GROUP BY t.id

sqlfiddle.com

上的示例

另请参阅：Force MySQL to return duplicates from WHERE IN clause without using JOIN/UNION?

当然，您的IN参数将是动态的，因此您必须为tmp表生成相应的SQL语句。

这是SQL的唯一方法。另一种可能性就是让您的查询与您的问题一样，然后以编程方式将行与传递给IN参数的计数相关联。

计数具有相同ID的重复项在一列中传递

2 个答案: