内部联接 - 单独的列

Question

我正在尝试 link 2 table 一起包含多个列。例如我有一个名为'wp_users'的table，我想将其用作主要table，另一个table 称为'CD2015_Occurrences'

我想link'wp_users'[EMAIL]到CD2015_Occurrences' [EMAIL] 这很简单，但我想添加内部联接。

所以它看起来像这样

电子邮件 |一季度 | Q2 | Q3 | Q4 |

电子邮件1 | 2 | 4 | 5 | 6

电子邮件2 | 4 | 5 | 6 | 0

等...

Table 'CD2015_Occurrences' 的内容是 Email, Quarter、总计

我需要以某种方式 link 通过电子邮件发送给 wp_users 并且每个季度有 4 个单独的栏。

我可能很好但这是我正在尝试做的事情：

    Select a.user_email
FROM wp_users AS a
INNER JOIN a.email
ON CD2015_Occurrences.email as b (SELECT quarter AS Q1 FROM CD2015_Occurrences where email = a.email and quarter = 'q1')
INNER JOIN a.email
ON CD2015_Occurrences.email as b (SELECT quarter AS Q2 FROM CD2015_Occurrences where email = a.email and quarter = 'q2')
INNER JOIN a.email
ON CD2015_Occurrences.email as b (SELECT quarter AS Q3 FROM CD2015_Occurrences where email = a.email and quarter = 'q3')
INNER JOIN a.email
ON CD2015_Occurrences.email as b (SELECT quarter AS Q4 FROM CD2015_Occurrences where email = a.email and quarter = 'q4')

有什么想法可以实现吗？如何实现？非常感谢最大值

Answer 1

SELECT users.email,
   SUM(IF(occurences.quarter='q1',occurences.total,0)) Q1,
   SUM(IF(occurences.quarter='q2',occurences.total,0)) Q2,
   SUM(IF(occurences.quarter='q3',occurences.total,0)) Q3,
   SUM(IF(occurences.quarter='q4',occurences.total,0)) Q4
FROM wp_users users
LEFT JOIN CD2015_Occurrences occurrences
ON users.email = occurrences.email
GROUP BY users.email

内部联接 - 单独的列

Inner Join - Separate Columns

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