SCHEMATA
SCHEMATA 表提供了关于数据库的信息。表中的数据与 SHOW DATABASES 语句的执行结果等价。
USE information_schema;
desc SCHEMATA;
+----------------------------+--------------+------+------+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------------------+--------------+------+------+---------+-------+
| CATALOG_NAME | varchar(512) | YES | | NULL | |
| SCHEMA_NAME | varchar(64) | YES | | NULL | |
| DEFAULT_CHARACTER_SET_NAME | varchar(64) | YES | | NULL | |
| DEFAULT_COLLATION_NAME | varchar(32) | YES | | NULL | |
| SQL_PATH | varchar(512) | YES | | NULL | |
+----------------------------+--------------+------+------+---------+-------+
5 rows in set (0.00 sec)
SELECT * FROM SCHEMATA;
+--------------+--------------------+----------------------------+------------------------+----------+
| CATALOG_NAME | SCHEMA_NAME | DEFAULT_CHARACTER_SET_NAME | DEFAULT_COLLATION_NAME | SQL_PATH |
+--------------+--------------------+----------------------------+------------------------+----------+
| def | INFORMATION_SCHEMA | utf8mb4 | utf8mb4_bin | NULL |
| def | METRICS_SCHEMA | utf8mb4 | utf8mb4_bin | NULL |
| def | mysql | utf8mb4 | utf8mb4_bin | NULL |
| def | PERFORMANCE_SCHEMA | utf8mb4 | utf8mb4_bin | NULL |
| def | test | utf8mb4 | utf8mb4_bin | NULL |
+--------------+--------------------+----------------------------+------------------------+----------+
5 rows in set (0.00 sec)
SCHEMATA 表各列字段含义如下：
- CATALOG_NAME：数据库归属的目录名，该列值永远为
def。 - SCHEMA_NAME：数据库的名字。
- DEFAULT_CHARACTER_SET_NAME：数据库的默认字符集。
- DEFAULT_COLLATION_NAME：数据库的默认 collation。
- SQL_PATH：该项值永远为
NULL。