What are the permission tables of mysql database?

MySQL database permission tables include: 1. user table, used to record account information allowed to connect to the server. All permissions enabled in this table are global level and apply to all databases; 2. db table , stores the user's operating permissions for a certain database; 3. tables_priv table, used to set permissions for a single table; 4. columns_priv table, used to set permissions for a single data column; 5. procs_priv table, used for storage Procedures and stored functions set permissions.

The operating system of this tutorial: Windows 10 system, mysql version 8.0, Dell G3 computer.

In the MySQL database, the permission tables include the user table, db table, tables_priv table, columns_priv table and procs_priv table.

1. User permission table

The user table is the most important permission table in MySQL, used to record account information that is allowed to connect to the server. It should be noted that all permissions enabled in the user table are global and apply to all databases.

The fields in the user table can be roughly divided into 4 categories, namely user columns, permission columns, security columns and resource control columns.

User column

The user column stores the information that users need to enter when connecting to the MySQL database. It should be noted that MySQL 5.7 version no longer uses Password as the password field, but changed it to authentication_string.

Permission column

The fields in the permission column determine the user's permissions and are used to describe the operations allowed on data and databases in the global scope.

Permissions are roughly divided into two categories, namely advanced management permissions and ordinary permissions:

• Advanced management permissions mainly manage the database, such as the permission to close services, Super permissions and loading users, etc.;

• Normal permissions mainly operate the database, such as query permissions, modification permissions, etc.

The permission columns of the user table include Select_priv, Insert_ priv and other fields ending with priv. The data type of these field values ​​is ENUM. The only possible values ​​are Y and N: Y represents the user There are corresponding permissions, N means that the user does not have the corresponding permissions. For security reasons, the default value for these fields is N.

If you want to modify the permissions, you can use the GRANT statement to grant some permissions to the user, or you can set the permissions by updating the user table with the UPDATE statement.

Security column

The security column is mainly used to determine whether the user can log in successfully. The security column in the user table is as shown in the following table:

##Record the time when the password was last modifiedpassword_lifetimesmallint (5) unsignedYESSet the password validity time in daysaccount_lockedenum('N','Y')NONWhether the user is locked (Y is locked, N is not locked)

Note: Even if password_expired is "Y", the user can still use the password to log in to MySQL, but no operations are allowed.

Usually standard distributions do not support ssl. Readers can use the SHOW VARIABLES LIKE "have_openssl" statement to check whether it has ssl functionality. If the value of have_openssl is DISABLED, the ssl encryption feature is not supported.

Resource control column

The fields of the resource control column are used to limit the resources used by users. The resource control columns in the user table are shown in Table 4.

Security columns of the user table

Field name	Field type	Is it empty	Default value	Description
ssl_type	enum('','ANY','X509','SPECIFIED')	NO		Support ssl standard encryption security field
ssl_cipher	blob	NO		Support ssl standard encryption security field
x509_issuer	blob	NO		Support x509 standard fields
x509_subject	blob	NO		Support x509 standard fields
plugin	char(64)	NO	mysql_native_password	Introducing plugins for password verification when users connect, plugin creates external/proxy users
password_expired	enum('N','Y')	NO	N	Whether the password has expired (N has not expired, y has expired)
password_last_changed	timestamp	YES

Resource control column of the user table

Field name	Field type	Whether it is empty	Default value	Description
max_questions	int(11) unsigned	NO	0	Specifies the number of query operations allowed per hour
max_updates	int(11) unsigned	NO	0	Specifies the number of update operations allowed per hour
max_connections	int(11) unsigned	NO	0	Specifies the number of connection operations allowed per hour
max_user_connections	int(11) unsigned	NO	0	Specifies the number of connections allowed to be established simultaneously

The default value of the above fields is 0, indicating no limit. If the number of user queries or connections exceeds the resource control limit within an hour, the user will be locked and cannot perform corresponding operations here until the next hour. The values ​​of these fields can be updated using the GRANT statement.

2. db table

The db table is commonly used and is a very important permissions table in the MySQL database. The table stores the user's operating permissions for a certain database. The fields in the table can be roughly divided into two categories, namely user columns and permission columns.

User column

db table user column has 3 fields, namely Host, User, and Db, which identify the operation permission of a user to connect to a certain database from a certain host. These 3 fields The combination of fields constitutes the primary key of the db table.

The user list of the db table is as shown in the following table:

##Dbchar(64)NONoneDatabase nameUserchar(32)NONoneUser name

Permission columns

The permission columns in the db table are roughly the same as those in the user table, except that the permissions in the user table are for all databases, while the permissions in the db table are only for the specified database. . If you want the user to have operation permissions only for a certain database, you can first set the corresponding permissions in the user table to N, and then set the operation permissions for the corresponding database in the db table.

3. tables_priv table

The tables_priv table is used to set permissions on a single table. The tables_priv table structure is as shown in the following table:

Field name	Field type	Is it empty?	Default value	Description
Host	char(60)	NO	None	Host name

Field name	Field type	Whether it is empty	Default value	Description
Host	char(60)	NO	None	Host
Db	char(64)	NO	None	Database name
User	char(32)	NO	None	Username
Table_name	char (64)	NO	None	Table name
Grantor	char(93)	NO	None	User who modified this record
Timestamp	timestamp	NO	CURRENT_TIMESTAMP	The time to modify the record
Table_priv	set('Select','Insert','Update' ,'Delete',' Create','Drop','Grant','References', 'Index','Alter','Create View','Show view','Trigger')	NO	None	Indicates the operation permissions on the table, including Select, Insert, Update, Delete, Create, Drop, Grant, References, Index and Alter, etc.
Column_priv	set('Select','Insert','Update','References')	NO	None	Indicates the operation permissions on the columns in the table, including Select, Insert, Update and References

4. columns_priv table

columns_priv table is used to set permissions on a single data column, columns_priv The table structure is as shown in the following table:

Field name	Field type	Is it empty	Default value	Description
Host	char(60)	NO	No	Host
Db	char(64)	NO	None	Database name
User	char(32)	NO	None	Username
Table_name	char(64)	NO	None	Table name
Column_name	char(64)	NO	None	Data column name, used to specify which data columns have operation permissions
Timestamp	timestamp	NO	CURRENT_TIMESTAMP	Modify the time of this record
Column_priv	set('Select','Insert','Update','References')	NO	None	Indicates the column in the table Operation permissions, including Select, Insert, Update and References

5. procs_priv table

The procs_priv table can set permissions on stored procedures and stored functions. The table structure of procs_priv is as shown in the table:

Field name	Field type	Whether it is empty	Default value	Description
Host	char(60)	NO	None	Host name
Db	char(64)	NO	None	Database name
User	char(32)	NO	None	Username
Routine_name	char(64)	NO	None	Indicates the name of the stored procedure or function
Routine_type	enum('FUNCTION','PROCEDURE')	NO	None	indicates the type of stored procedure or function. The Routine_type field has two values, namely FUNCTION and PROCEDURE . FUNCTION indicates that this is a function; PROCEDURE indicates that this is a stored procedure.
Grantor	char(93)	NO	None	User who inserted or modified this record
Proc_priv	set('Execute','Alter Routine','Grant')	NO	None	indicates the permissions you have, including Execute, Alter Routine, and Grant.
Timestamp	timestamp	NO	CURRENT_TIMESTAMP	indicates the record update time

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