45 lines
2.3 KiB
Markdown
45 lines
2.3 KiB
Markdown
---
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title: SQL Group By Statement
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localeTitle: SQL Group By Statement
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---
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## SQL Group By Statemet
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### 使用示例
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GROUP BY为我们提供了一种组合行和聚合数据的方法。
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使用的数据来自我们在其中一些指南中使用的广告系列贡献数据。
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以下SQL语句正在回答这个问题：“哪些候选人在2016年获得的捐款总额最大，但只有那些拥有超过2000万美元的捐款？”
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以降序（DESC）顺序对此数据集进行排序会将总贡献最大的候选项放在列表顶部。
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```sql
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SELECT Candidate, Election_year, sum(Total_$), count(*)
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FROM combined_party_data
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WHERE Election_year = 2016
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GROUP BY Candidate, Election_year -- this tells the DBMS to summarize by these two columns
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HAVING sum(Total_$) > 20000000 -- limits the rows presented from the summary of money ($20 Million USD)
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ORDER BY sum(Total_$) DESC; -- orders the presented rows with the largest ones first.
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```
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```text
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+--------------------------------------------------+---------------+-------------------+----------+
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| Candidate | Election_year | sum(Total_$) | count(*) |
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+--------------------------------------------------+---------------+-------------------+----------+
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| CLINTON, HILLARY RODHAM & KAINE, TIMOTHY M (TIM) | 2016 | 568135094.4400003 | 126 |
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| TRUMP, DONALD J & PENCE, MICHAEL R (MIKE) | 2016 | 366853142.7899999 | 114 |
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| SANDERS, BERNARD (BERNIE) | 2016 | 258562022.17 | 122 |
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| CRUZ, RAFAEL EDWARD (TED) | 2016 | 93430700.29000005 | 104 |
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| CARSON, BENJAMIN S (BEN) | 2016 | 62202411.12999996 | 93 |
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| RUBIO, MARCO ANTONIO | 2016 | 44384313.9 | 106 |
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| BUSH, JOHN ELLIS (JEB) | 2016 | 34606731.78 | 97 |
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+--------------------------------------------------+---------------+-------------------+----------+
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7 rows in set (0.01 sec)
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```
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与所有这些SQL事物一样，它们比本入门指南中的内容更多。
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我希望这至少足以让你开始。
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请参阅您的数据库管理员手册，并自己尝试不同的选项。 |