27 lines
434 B
Markdown
27 lines
434 B
Markdown
## 题目
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编写一个 SQL 查询，查找 Person 表中所有重复的电子邮箱。
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示例：
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```
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+----+---------+
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| Id | Email |
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+----+---------+
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| 1 | a@b.com |
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| 2 | c@d.com |
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| 3 | a@b.com |
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+----+---------+
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```
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根据以上输入，你的查询应返回以下结果：
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```
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+---------+
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| Email |
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+---------+
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| a@b.com |
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+---------+
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```
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## 答案
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```sql
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select Email from Person group by Email having count(*) > 1
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```
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