PostgreSQL DISTINCT 关键字。不如你甜如蜜
作者：互联网
在 PostgreSQL 中，DISTINCT 关键字与 SELECT 语句一起使用，用于去除重复记录，只获取唯一的记录。
我们平时在操作数据时，有可能出现一种情况，在一个表中有多个重复的记录，当提取这样的记录时，DISTINCT 关键字就显得特别有意义，它只获取唯一一次记录，而不是获取重复记录。
语法
用于去除重复记录的 DISTINCT 关键字的基本语法如下：
SELECT DISTINCT column1, column2,.....columnN
FROM table_name
WHERE [condition]
实例
创建 COMPANY 表（下载 COMPANY SQL 文件 ），数据内容如下：
http://m.douguo.com/recipe/amp/2902447
http://m.douguo.com/recipe/mip/2902447
http://m.douguo.com/recipe/amp/2902457
http://m.douguo.com/recipe/mip/2902457
http://m.douguo.com/recipe/amp/2902481
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http://m.douguo.com/recipe/amp/2902525
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http://m.douguo.com/recipe/amp/2902737
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http://m.douguo.com/recipe/amp/2902755
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http://m.douguo.com/recipe/amp/2902787
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http://m.douguo.com/recipe/amp/2903180
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http://m.douguo.com/recipe/amp/2904910
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http://m.douguo.com/recipe/amp/2904915
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http://m.douguo.com/recipe/amp/2904928
http://m.douguo.com/recipe/mip/2904928
http://m.douguo.com/recipe/amp/2904931
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http://m.douguo.com/recipe/amp/2904950
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http://m.douguo.com/recipe/amp/2904953
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http://m.douguo.com/recipe/amp/2904954
http://m.douguo.com/recipe/mip/2904954
http://m.douguo.com/recipe/amp/2904974
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http://m.douguo.com/recipe/amp/2905345
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http://m.douguo.com/recipe/amp/2905425
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http://m.douguo.com/recipe/amp/2905543
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http://m.douguo.com/recipe/amp/2905563
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http://m.douguo.com/recipe/amp/2905566
http://m.douguo.com/recipe/mip/2905566
http://m.douguo.com/recipe/amp/2905577
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http://m.douguo.com/recipe/amp/2905598
http://m.douguo.com/recipe/mip/2905598
http://m.douguo.com/recipe/amp/2905670
http://m.douguo.com/recipe/mip/2905670
http://m.douguo.com/recipe/amp/2905686
http://m.douguo.com/recipe/mip/2905686
http://m.douguo.com/recipe/amp/2905702
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http://m.douguo.com/recipe/amp/2905721
http://m.douguo.com/recipe/mip/2905721
http://m.douguo.com/recipe/amp/2905733
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http://m.douguo.com/recipe/amp/2905764
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http://m.douguo.com/recipe/amp/2905765
http://m.douguo.com/recipe/mip/2905765
http://m.douguo.com/recipe/amp/2905787
http://m.douguo.com/recipe/mip/2905787
http://m.douguo.com/recipe/amp/2905801
http://m.douguo.com/recipe/mip/2905801
http://m.douguo.com/recipe/amp/2905815
http://m.douguo.com/recipe/mip/2905815
http://m.douguo.com/recipe/amp/2905823
http://m.douguo.com/recipe/mip/2905823
http://m.douguo.com/recipe/amp/2905835
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http://m.douguo.com/recipe/amp/2905858
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http://m.douguo.com/recipe/mip/2905948
http://m.douguo.com/recipe/amp/2905956
http://m.douguo.com/recipe/mip/2905956
http://m.douguo.com/recipe/amp/2905959
http://m.douguo.com/recipe/mip/2905959
http://m.douguo.com/recipe/amp/2905964
http://m.douguo.com/recipe/mip/2905964
http://m.douguo.com/recipe/amp/2906042
http://m.douguo.com/recipe/mip/2906042
标签：PostgreSQL,DISTINCT,recipe,douguo,mip,amp,如蜜,http,com 来源： https://www.cnblogs.com/guger/p/13431064.html