# Mysql Database 

+ User account and corresponding authorization information
  + `mysql.user` : User account, global privileges, and other non-privileged columns
  + `mysql.db` : Database-level privilege
  + `mysql.tables_priv` : Table-level privilege
  + `mysql.columns_priv` : Column-level privilege (currently not supported)

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mysql database
mysql.user\ mysql.db\ mysql.tables_priv\ mysql.columns_priv
- The above 4 system tables are consistent with MySQL database compatibility.
- The system table contains user account and corresponding authorization information
  - user user account, global privileges, and some other non-privileged columns
  - DB database-level privilege
  - tables_priv table-level privilege
  - columns_priv column-level privilege
- Tables can be edited directly via DML SQL statements
MySQL.global_variables
- View TiDB global variables through the system table
- modify of VARIABLE_VALUE in the system table is not supported