mysql - 如何仅提取所有电子邮件条目丢失的记录

Question

我有一个问题，所以我有这张桌子：

| Manager_Name | Email_Address |
| ------------ | ------------- |
| person A     |[e-mail]|
| person A     |Null|
| person A     |Null|
| person A     |[e-mail]|
| person A     |[e-mail]|
| person B     |Null|
| person B     |Null|
| person B     |Null|
| person B     |Null|
| person B     |Null|
| person C     |[e-mail]|
| person C     |[e-mail]|
| person C     |[e-mail]|
| person C     |[e-mail]|
| person C     |[e-mail]|
| person D     |Null|
| person D     |Null|
| person D     |Null|
| person D     |Null|
| person D     |Null|

我的问题是如何仅提取所有 5 个电子邮件地址都丢失的经理，如 B 人和 D 人，在原始表中我有很多我只想得到所有 5 个地址都丢失的经理。

标签： mysqlgroup-bymaxhavingsql-null

Answer 1

您可以在子句中分组Manager_Name并设置条件：HAVING

SELECT Manager_Name
FROM tablename
GROUP BY Manager_Name
HAVING MAX(Email_Address) IS NULL;

请参阅演示。