MySQL查詢顯示兩列中的重複信息

Question

我需要計算列A中有重複記錄的行數，而列B必須是1並且也要被複制。

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` 

假設你有這些表在MySQL爲myTable：

/---------------------------------/ 
|  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 | 
/---------------------------------/ 

的結果必須是4，因爲只有ID 1，3，5和6的重複兩列和columnB的條件必須總是等於1

我的PHP代碼給結果：

$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：

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;