計數和列名

Question

我查詢

SELECT COUNT(DISTINCT alloc.[code4]) AS countcode4,code4, table2.itemid as tbitemid2 
    FROM table1,table 2 
WHERE table1.id=table2.id 
GROUP BY code4, tbitemid2 

我想查詢給我計數，並返回只有1「碼4」

如何做到這一點的實例？

感謝 Mithil

Answer 1

刪除code4] from the組by`，並使用聚合函數：

SELECT COUNT(DISTINCT alloc.[code4]) AS countcode4, min(code4) as code4, 
     table2.itemid as tbitemid2 
FROM table1 join 
    table2 
    on table1.id = table2.id 
GROUP BY tbitemid2; 

我不知道什麼是alloc;它來自您的示例查詢。