Use the PostgreSQL GRANT command to modify permissions on various database objects

在PostgreSQL中,A user must have LOGIN权限to log into the database.然而,Explicit permissions must be assigned to perform database operations,Include selection table、列和记录.

PostgreSQL的GRANTQueries allow you to modify a user's permissions on database objects,如表、列、视图、函数、架构等等.

This tutorial will guide you to use itPostgreSQL GRANTcommands to modify permissions on various database objects.

基本用法

GRANT命令的基本语法是

GRANT privilege(s) ON object(s) TO user
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在上面的语法中,You can specify one or more permissions to grant users permissions on specified objects.

To set all permissions on an object,可以使用ALL关键字.

Some of the permissions you can specify to grant on an object include.

1. SELECT
2. INSERT
3. 更新
4. DELETE
5. 创建
6. 连接
7. 触发器
8. TRUNCATE
9. 引用
10. 执行

接下来,You specify the database object and user to grant this set of permissions.

Grant statement example

让我们看一下如何在PostgreSQL数据库中使用GRANT查询的几个例子.

首先,Create a local user without permissions.要做到这一点,Make sure you are logged in as an admin user.

psql -U postgres
CREATE ROLE mods LOGIN PASSWORD 'hello';
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在下一步,Create a sample database and tables,We will use it to illustratePostgreSQL的权限.

Below is an example query.

DROP DATABASE IF EXISTS privs;
CREATE DATABASE privs;
\c privs;
CREATE TABLE modify (id SERIAL, username VARCHAR(255) NOT NULL, email VARCHAR(255) NOT NULL, amount INT, PRIMARY KEY(id));
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最后,退出Postgres用户,Log in as the user we just created above.在上面的例子中,使用以下命令.

psql -U mods -d privs;
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例1

如果你试图从privs数据库的modifySelect a value from the table,You will get a permission denied error.

比如说

privs=> select * from modify;
ERROR:  permission denied for table modify
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You can pass grantmodsUser all rights or increase select rights to solve this error.

要做到这一点,请以Postgres用户的身份登录.

psql -U postgres -d privs;
GRANT SELECT ON modify TO mods;
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这允许mods用户从privs数据库的modifySelect an item from the table.

一旦你运行select语句,You should get the following result.

privs=# SELECT * FROM modify;
id | username | email | amount
----+----------+-------+--------
(0 rows)
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例2

You can also specify multiple permissions at once.例如,要指定SELECT、INSERT、DELETE和TRUNCATE的权限,使用命令.

GRANT SELECT, INSERT, DELETE, TRUNCATE ON modify TO mods;
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例3

To grant all permissions to a user,Please set permissions to ALL,As shown in the command example below.

GRANT ALL ON modify TO mods;
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例4

在上面的所有例子中,We only assigned permissions to a user on a specific table.If you want to grant permissions on all tables of the specified schema,我们可以使用命令.

GRANT SELECT, INSERT, DELETE, TRUNCATE ON ALL TABLES IN SCHEMA "privs" TO mods;
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例5

You can also assign a connection permissionGRANTto a specific user,Get him into a specific database.查询方式是

GRANT CONNECT ON DATABASE privs TO mods;
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To revoke all permissions granted to a user,可以使用REVOKE查询.

REVOKE SELECT, INSERT, DELETE, TRUNCATE ON modify FROM mods;
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结束

as this guide shows,PostgreSQL允许你使用GRANT和REVOKEcommand to modify user permissions on database objects.