标签：mip PostgreSQL DISTINCT recipe douguo 关键字 amp http com

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
http://m.douguo.com/recipe/mip/2902481
http://m.douguo.com/recipe/amp/2902482
http://m.douguo.com/recipe/mip/2902482
http://m.douguo.com/recipe/amp/2902491
http://m.douguo.com/recipe/mip/2902491
http://m.douguo.com/recipe/amp/2902525
http://m.douguo.com/recipe/mip/2902525
http://m.douguo.com/recipe/amp/2902524
http://m.douguo.com/recipe/mip/2902524
http://m.douguo.com/recipe/amp/2902555
http://m.douguo.com/recipe/mip/2902555
http://m.douguo.com/recipe/amp/2902585
http://m.douguo.com/recipe/mip/2902585
http://m.douguo.com/recipe/amp/2902587
http://m.douguo.com/recipe/mip/2902587
http://m.douguo.com/recipe/amp/2902601
http://m.douguo.com/recipe/mip/2902601
http://m.douguo.com/recipe/amp/2902633
http://m.douguo.com/recipe/mip/2902633
http://m.douguo.com/recipe/amp/2902639
http://m.douguo.com/recipe/mip/2902639
http://m.douguo.com/recipe/amp/2902661
http://m.douguo.com/recipe/mip/2902661
http://m.douguo.com/recipe/amp/2902695
http://m.douguo.com/recipe/mip/2902695
http://m.douguo.com/recipe/amp/2902699
http://m.douguo.com/recipe/mip/2902699
http://m.douguo.com/recipe/amp/2902719
http://m.douguo.com/recipe/mip/2902719
http://m.douguo.com/recipe/amp/2902737
http://m.douguo.com/recipe/mip/2902737
http://m.douguo.com/recipe/amp/2902755
http://m.douguo.com/recipe/mip/2902755
http://m.douguo.com/recipe/amp/2902783
http://m.douguo.com/recipe/mip/2902783
http://m.douguo.com/recipe/amp/2902787
http://m.douguo.com/recipe/mip/2902787
http://m.douguo.com/recipe/amp/2903180
http://m.douguo.com/recipe/mip/2903180
http://m.douguo.com/recipe/amp/2903315
http://m.douguo.com/recipe/mip/2903315
http://m.douguo.com/recipe/amp/2903334
http://m.douguo.com/recipe/mip/2903334
http://m.douguo.com/recipe/amp/2903336
http://m.douguo.com/recipe/mip/2903336
http://m.douguo.com/recipe/amp/2903341
http://m.douguo.com/recipe/mip/2903341
http://m.douguo.com/recipe/amp/2904138
http://m.douguo.com/recipe/mip/2904138
http://m.douguo.com/recipe/amp/2904163
http://m.douguo.com/recipe/mip/2904163
http://m.douguo.com/recipe/amp/2904164
http://m.douguo.com/recipe/mip/2904164
http://m.douguo.com/recipe/amp/2904189
http://m.douguo.com/recipe/mip/2904189
http://m.douguo.com/recipe/amp/2904210
http://m.douguo.com/recipe/mip/2904210
http://m.douguo.com/recipe/amp/2904216
http://m.douguo.com/recipe/mip/2904216
http://m.douguo.com/recipe/amp/2904238
http://m.douguo.com/recipe/mip/2904238
http://m.douguo.com/recipe/amp/2904242
http://m.douguo.com/recipe/mip/2904242
http://m.douguo.com/recipe/amp/2904254
http://m.douguo.com/recipe/mip/2904254
http://m.douguo.com/recipe/amp/2904258
http://m.douguo.com/recipe/mip/2904258
http://m.douguo.com/recipe/amp/2904261
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http://m.douguo.com/recipe/amp/2904276
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http://m.douguo.com/recipe/amp/2904349
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http://m.douguo.com/recipe/amp/2904357
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http://m.douguo.com/recipe/amp/2904392
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http://m.douguo.com/recipe/amp/2904409
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http://m.douguo.com/recipe/amp/2904422
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http://m.douguo.com/recipe/amp/2904428
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http://m.douguo.com/recipe/amp/2904466
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http://m.douguo.com/recipe/amp/2904478
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http://m.douguo.com/recipe/amp/2904480
http://m.douguo.com/recipe/mip/2904480
http://m.douguo.com/recipe/amp/2904513
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http://m.douguo.com/recipe/amp/2904514
http://m.douguo.com/recipe/mip/2904514
http://m.douguo.com/recipe/amp/2904548
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http://m.douguo.com/recipe/amp/2904560
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http://m.douguo.com/recipe/amp/2904605
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http://m.douguo.com/recipe/amp/2904634
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http://m.douguo.com/recipe/amp/2904639
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http://m.douguo.com/recipe/amp/2904657
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http://m.douguo.com/recipe/amp/2904660
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http://m.douguo.com/recipe/amp/2904694
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http://m.douguo.com/recipe/amp/2904699
http://m.douguo.com/recipe/mip/2904699
http://m.douguo.com/recipe/amp/2904740
http://m.douguo.com/recipe/mip/2904740
http://m.douguo.com/recipe/amp/2904774
http://m.douguo.com/recipe/mip/2904774
http://m.douguo.com/recipe/amp/2904776
http://m.douguo.com/recipe/mip/2904776
http://m.douguo.com/recipe/amp/2904796
http://m.douguo.com/recipe/mip/2904796
http://m.douguo.com/recipe/amp/2904835
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http://m.douguo.com/recipe/amp/2904849
http://m.douguo.com/recipe/mip/2904849
http://m.douguo.com/recipe/amp/2904879
http://m.douguo.com/recipe/mip/2904879
http://m.douguo.com/recipe/amp/2904887
http://m.douguo.com/recipe/mip/2904887
http://m.douguo.com/recipe/amp/2904910
http://m.douguo.com/recipe/mip/2904910
http://m.douguo.com/recipe/amp/2904915
http://m.douguo.com/recipe/mip/2904915
http://m.douguo.com/recipe/amp/2904928
http://m.douguo.com/recipe/mip/2904928
http://m.douguo.com/recipe/amp/2904931
http://m.douguo.com/recipe/mip/2904931
http://m.douguo.com/recipe/amp/2904950
http://m.douguo.com/recipe/mip/2904950
http://m.douguo.com/recipe/amp/2904953
http://m.douguo.com/recipe/mip/2904953
http://m.douguo.com/recipe/amp/2904954
http://m.douguo.com/recipe/mip/2904954
http://m.douguo.com/recipe/amp/2904974
http://m.douguo.com/recipe/mip/2904974
http://m.douguo.com/recipe/amp/2904975
http://m.douguo.com/recipe/mip/2904975
http://m.douguo.com/recipe/amp/2905002
http://m.douguo.com/recipe/mip/2905002
http://m.douguo.com/recipe/amp/2905026
http://m.douguo.com/recipe/mip/2905026
http://m.douguo.com/recipe/amp/2905028
http://m.douguo.com/recipe/mip/2905028
http://m.douguo.com/recipe/amp/2905345
http://m.douguo.com/recipe/mip/2905345
http://m.douguo.com/recipe/amp/2905357
http://m.douguo.com/recipe/mip/2905357
http://m.douguo.com/recipe/amp/2905425
http://m.douguo.com/recipe/mip/2905425
http://m.douguo.com/recipe/amp/2905501
http://m.douguo.com/recipe/mip/2905501
http://m.douguo.com/recipe/amp/2905535
http://m.douguo.com/recipe/mip/2905535
http://m.douguo.com/recipe/amp/2905537
http://m.douguo.com/recipe/mip/2905537
http://m.douguo.com/recipe/amp/2905543
http://m.douguo.com/recipe/mip/2905543
http://m.douguo.com/recipe/amp/2905563
http://m.douguo.com/recipe/mip/2905563
http://m.douguo.com/recipe/amp/2905566
http://m.douguo.com/recipe/mip/2905566
http://m.douguo.com/recipe/amp/2905577
http://m.douguo.com/recipe/mip/2905577
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
http://m.douguo.com/recipe/mip/2905702
http://m.douguo.com/recipe/amp/2905721
http://m.douguo.com/recipe/mip/2905721
http://m.douguo.com/recipe/amp/2905733
http://m.douguo.com/recipe/mip/2905733
http://m.douguo.com/recipe/amp/2905764
http://m.douguo.com/recipe/mip/2905764
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
http://m.douguo.com/recipe/mip/2905835
http://m.douguo.com/recipe/amp/2905858
http://m.douguo.com/recipe/mip/2905858
http://m.douguo.com/recipe/amp/2905859
http://m.douguo.com/recipe/mip/2905859
http://m.douguo.com/recipe/amp/2905909
http://m.douguo.com/recipe/mip/2905909
http://m.douguo.com/recipe/amp/2906023
http://m.douguo.com/recipe/mip/2906023
http://m.douguo.com/recipe/amp/2906060
http://m.douguo.com/recipe/mip/2906060
http://m.douguo.com/recipe/amp/2906061
http://m.douguo.com/recipe/mip/2906061
http://m.douguo.com/recipe/amp/2906115
http://m.douguo.com/recipe/mip/2906115
http://m.douguo.com/recipe/amp/2902698
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http://m.douguo.com/recipe/amp/2902838
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http://m.douguo.com/recipe/amp/2902932
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http://m.douguo.com/recipe/amp/2902953
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http://m.douguo.com/recipe/amp/2903021
http://m.douguo.com/recipe/mip/2903021
http://m.douguo.com/recipe/amp/2903164
http://m.douguo.com/recipe/mip/2903164
http://m.douguo.com/recipe/amp/2903243
http://m.douguo.com/recipe/mip/2903243
http://m.douguo.com/recipe/amp/2903249
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http://m.douguo.com/recipe/amp/2903302
http://m.douguo.com/recipe/mip/2903302
http://m.douguo.com/recipe/amp/2903405
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http://m.douguo.com/recipe/amp/2903445
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http://m.douguo.com/recipe/amp/2903453
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http://m.douguo.com/recipe/amp/2903608
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http://m.douguo.com/recipe/amp/2903614
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http://m.douguo.com/recipe/amp/2903638
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http://m.douguo.com/recipe/amp/2903682
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http://m.douguo.com/recipe/amp/2903708
http://m.douguo.com/recipe/mip/2903708
http://m.douguo.com/recipe/amp/2903746
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http://m.douguo.com/recipe/amp/2903767
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http://m.douguo.com/recipe/amp/2903787
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http://m.douguo.com/recipe/amp/2903818
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http://m.douguo.com/recipe/amp/2903847
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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：mip,PostgreSQL,DISTINCT,recipe,douguo,关键字,amp,http,com
来源： https://www.cnblogs.com/guger/p/13431065.html

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