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The following content mainly brings you what information_schema database is used for. The knowledge mentioned is slightly different from books. It is summarized by professional technicians in the process of contacting users. It has certain experience sharing value and hopes to bring help to readers.

When you install or use MYSQL, you will find that in addition to your installed database, there is also an information_schema database. What is the information_schema database for? WordPress bloggers might wonder, is it a database added by an installation template? After reading this article, you will know something about the information_schema database.

The information_schema database comes with MySQL and provides access to database metadata. What is metadata? Metadata is data about data, such as database or table names, column data types, or access rights. Other terms sometimes used to describe this information include "data dictionary" and "system catalog."

In MySQL, the information_schema is thought of as a database, specifically an information database. It holds information about all other databases maintained by MySQL Cloud Virtual Machine. Such as database name, database table, table column data type and access rights, etc. In INFORMATION_SCHEMA, there are several read-only tables. They are actually views, not base tables, so you won't be able to see any files associated with them.

information_schema Database table description:

SCHEMATA table: Provides information about all databases in the current instance of mysql. The results of show databases are taken from this table.

TABLES tables: Provides information about tables in the database, including views. Details which schema a table belongs to, table type, table engine, creation time and other information. Show tables from schemame.

COLUMNS Table: Provides column information in the table. Details all columns of a table and information about each column. is the result of show columns from schemaname.tablename taken from this table.

STATISTICS Table: Provides information about the table index. is the result of show index from schemaname.tablename taken from this table.

USER_PRIVILEGES table: Gives information about global permissions. This information is derived from the mysql.user authorization table. Non-standard table.

SCHEMA_PRIVILEGES table: Gives information about schema (database) permissions. This information comes from the mysql.db authorization table. Non-standard table.

TABLE_PRIVILEGES table: Gives information about table permissions. This information is derived from the mysql.tables_priv authorization table. Non-standard table.

COLUMN_PRIVILEGES table: Gives information about column permissions. This information is derived from the mysql.columns_priv authorization table. Non-standard table.

CHARACTER_SETS table: Provides information about the character sets available for mysql instances. is the SHOW CHARACTER SET result set taken from this table.

COLLATIONS table: Provides information about the collation of character sets.

COLLATION_CHARACTER_SET_APPLICATION table: Indicates the character set available for collation. These columns are equivalent to the first two display fields of SHOW COLLATION.

TABLE_CONSTRAINTS table: Describes the table where constraints exist. And the constraint type of the table.

KEY_COLUMN_USAGE table: Describes key columns with constraints.

ROUTINES table: Provides information about stored subroutines (stored procedures and functions). At this point, the ROUTINES table does not contain custom functions (UDFs). A column named "mysql.proc name" indicates the mysql.proc table column corresponding to the INFORMATION_SCHEMA.ROUTINES table.

VIEWS table: Gives information about views in the database. You need show views permission, otherwise you cannot view view information.

TRIGGERS table: provides information about triggers. You must have super permission to view this table

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