PostgreSQL 删除check约束的实现

这篇文章主要介绍了PostgreSQL 删除check约束的实现，具有很好的参考价值，希望对大家有所帮助。一起跟随小编过来看看吧。

删除check约束：

1.\d table_name 查找约束名称

\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";

补充：PostgreSQL查询约束和创建删除约束

查询约束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有四种：

UNIQUE、PRIMARY KEY、CHECK、FOREIGN KEY, 通过修改上边sql语句的table_name和constraint_type来进行相应的查询。

添加约束

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

删除约束

1alter table table_name drop constraint if EXISTS uk_users_name1;

文章来源：脚本之家

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