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這篇文章主要介紹了PostgreSQL 刪除check約束的實現(xiàn)，具有很好的參考價值，希望對大家有所幫助。一起跟隨小編過來看看吧。

刪除check約束：

1.\d table_name 查找約束名稱

\d dm_alarms_fct_20170613 "dm_alarms_fct_20170613_dm_transct_date_key_check"

2.alter table .. drop constraint ..

1ALTER TABLE "dm_alarms_fct_20170613" Drop constraint "dm_alarms_fct_20170613_dm_transct_date_key_check";

補(bǔ)充：PostgreSQL查詢約束和創(chuàng)建刪除約束

查詢約束constraint

SELECT
   tc.constraint_name, tc.table_name, kcu.column_name,
   ccu.table_name AS foreign_table_name,
   ccu.column_name AS foreign_column_name,
   tc.is_deferrable,tc.initially_deferred
 FROM
   information_schema.table_constraints AS tc
   JOIN information_schema.key_column_usage AS kcu ON tc.constraint_name = kcu.constraint_name
   JOIN information_schema.constraint_column_usage AS ccu ON ccu.constraint_name = tc.constraint_name
 WHERE constraint_type = 'UNIQUE' AND tc.table_name = 'table_name';

constraint_type有四種：

UNIQUE、PRIMARY KEY、CHECK、FOREIGN KEY, 通過修改上邊sql語句的table_name和constraint_type來進(jìn)行相應(yīng)的查詢。

添加約束

1ALTER TABLE table_name ADD CONSTRAINT uk_users_name1 UNIQUE (NAME);

刪除約束

1alter table table_name drop constraint if EXISTS uk_users_name1;

文章來源：腳本之家

來源地址：https://www.jb51.net/article/205217.htm

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