Question

我正在使用Expression Engine和查询模块，它允许您使用MySQL来获得结果。我有一组数据，我试图与用户关联。我的查询目前如下：

SELECT COUNT(*) 
FROM exp_channel_grid_field_11 
INNER JOIN exp_member_data 
WHERE `col_id_12` = 'Race' && `member_id` = '1'

所以，在谈到加入时，我并没有太多关注，但我只是在寻找计数。感谢。

Answer 1

不确定你追求的是什么 - 你don't necessarily need an 'ON' to do a JOIN但是你可能需要定义表格。我不知道哪些列属于哪些表（也没有mysql，也许这就是问题）
假设'member_id'在exp_member_data中并且'col_id_12'在exp_channel_grid_field_11中，您可能需要执行以下操作：

SELECT COUNT(*)
 FROM exp_channel_grid_field_11
 INNER JOIN exp_member_data
 WHERE `exp_channel_grid_field_11.col_id_12` = 'Race'
 && `exp_member_data.member_id` = '1'

你可以用“表别名”“漂亮起来”，比如这样：

SELECT COUNT(*)
 FROM exp_channel_grid_field_11 e11
 INNER JOIN exp_member_data ed
 WHERE `e11.col_id_12` = 'Race'
 AND `ed.member_id` = '1'

或者，也许应该有'ON'member_id？

SELECT COUNT(*)
 FROM exp_channel_grid_field_11 e11
 INNER JOIN exp_member_data ed  
 ON e11.member_id = ed.member_id  
 WHERE `e11.col_id_12` = 'Race'
 AND `ed.member_id` = '1'

Answer 2

代替WHERE col_id_12 = 'Race'，使用：on col_id_12 = 'Race'

 SELECT COUNT(*) 
 FROM exp_channel_grid_field_11 
 INNER JOIN exp_member_data ON `col_id_12` = 'Race' 
 WHERE `member_id` = '1'

简单MySQL连接的问题

2 个答案: