使用MySQL和PHP从结果中删除重复项

Question

我在下面给出了一个查询

SELECT A.order_no, A.order_date,
COUNT(B.reaction_no) as tot_reaction_no, 
SUM(CASE 
WHEN (B.purification != '') THEN 1 
ELSE 0  
END) as tot_purification 
FROM order_header A
LEFT JOIN order_reactions B ON A.order_no = B.order_no
WHERE A.order_date BETWEEN '2015-10-01 00:00:00' AND '2016-09-01 00:00:00' 
AND A.order_no = '23746'
GROUP BY  A.order_no

这将产生如图所示的结果。但结果是错误的，因为有些条目是重复的。所以我必须删除副本并打印计数。所需的计数是表1中“列”的计数。

Answer 1

我认为你需要在你的选择中省略A.order_date，或者你应该将它添加到group by子句中。这会给你一个不同的结果。

您也可以在select子句中使用子查询：

SELECT A.order_no, A.order_date, COUNT(B.reaction_no) as tot_reaction_no, (SELECT count(*) FROM order_reactions as or WHERE or.order_no=A.order_no AND purification!='') as tot_purification, (SELECT count(*) FROM order_reactions as or2 WHERE or.order_no=A.order_no) as tot_reaction_no FROM order_header A WHERE A.order_date BETWEEN '2015-10-01 00:00:00' AND '2016-09-01 00:00:00' AND A.order_no = '23746'

这只是我的头脑，因为你的截图没有显示完整的表格，我不确定这是100％正确，但它可能会指向正确的方向。

Answer 2

我会提出查询

 SELECT COUNT(DISTINCT clone_name) AS tot_purification, COUNT(*) AS tot_reaction_no FROM Table2 WHERE `purification`='Column' AND `order_no`=23746;

请原谅引用中的错误，在引用imo时，MySQL非常混乱。

编辑：

添加了AS tot_purification

我不确定你期望的是什么作为tot_reaction_no，所以我只计算了订单和净化匹配的所有行，如我的WHERE子句中所述。

Answer 3

因为您只对 A.order_no 进行分组，请在查询中进行以下更改，然后重试：

替换行：

GROUP BY A.order_no;

到

GROUP BY A.order_no, A.clone_name;