Question

我有两个不同的表，每个表都有一个名为id_product的列。如何在两个表中获取id_field的DISTINCT值？

tb_compare
-id_product

tb_product_field 
-id_product
-id_field


 $qasql1 = mysql_query("SELECT c1.*,
           c2.DISTINCT(id_field) FROM  tb_compare AS c1 
           INNER JOIN tb_product_field AS c2 ON c1.id_product=c2.id_product 
           WHERE c1.compareSession = '$sessionID'  ORDER BY c1.compareID Desc "
          );

谢谢！

Answer 1

您可以使用union：

select id_product
from tb_compare
union
select id_product
from tb_product_field;

请注意，union会删除列表中的重复行，因此不需要distinct。在这种情况下，一行只包含一个值。

Answer 2

首先加入两个表，然后执行子查询：

SELECT DISTINCT id_field FROM
    (SELECT * FROM tb_compare AS c1 
        INNER JOIN tb_product_field AS c2 
        ON c1.id_product=c2.id_product 
        WHERE c1.compareSession = '$sessionID' 
        ORDER BY c1.compareID Desc
     )

Answer 3

我找到了一个解决方案，我尝试将GROUP BY改为ORDER BY，然后删除DINSTINCT。

$qasql1 = mysql_query("SELECT c1.*,
       c2.id_field FROM  tb_compare AS c1 
       INNER JOIN tb_product_field AS c2 ON c1.id_product=c2.id_product 
       WHERE c1.compareSession = '$sessionID' GROUP BY c1.compareID Desc "
      );

感谢所有人。

SELECT两个表区别。 MySQL的

3 个答案: