MySQL查询在两列中显示重复项

Question

我需要计算列A中重复记录的行数，列B必须为1，并且还必须重复。

SELECT COUNT(*) as num
FROM myTable
WHERE (columnB = 1 GROUP BY columnB HAVING COUNT(id_myTable) > 1) AND (columnA IN (SELECT columnA FROM myTable GROUP BY columnA HAVING COUNT(id_myTable) > 1))
ORDER BY columnC ASC`

假设您在MySQL中有这些名为myTable的表：

/---------------------------------/
|      id    | ColumnA | Column B |
|---------------------------------|
|          1 | Andre   |        1 |
|          2 | Joao    |        2 |
|          3 | Maria   |        1 |
|          4 | Joao    |        1 |
|          5 | Andre   |        1 |
|          6 | Maria   |        1 |
|          7 | Andre   |        2 |
/---------------------------------/

结果必须为4，因为只有id 1,3,5和6两列都重复，而columnB的条件必须始终等于1.

我的PHP代码给出结果：

$query = "select sum(c) from (select count(1) as c from myTable group by columnA, columnB having count(1) > 1 and columnB = 1) t"; $total_pages = mysql_fetch_array(mysql_query($query)); $total_pages = $total_pages[c]; $total_rows = $total_pages;

Answer 1

select sum(c) from (
                     select count(1) as c from myTable  
                     group by ColumnA, ColumnB 
                     having count(1) > 1 and ColumnB=1
                    ) t

Answer 2

我相信你想要：

select sum(cnt)
from (select columnA, columnB, count(*) as cnt
      from myTable
      where columnB = 1
      group by columnA, columnB
      having count(*) > 1  -- or do you mean `count(*) = 2`?
     ) ab;