#查看
数据库版本
mysql> select @@version;
+------------+
| @@version |
+------------+
| 5.5.16-log |
+------------+
1 row in set (0.00 sec)
mysql> select * from information_schema.schemata; # 保存了
系统的所有的数据库名 ，关键的字段是schema_name
# 2 rows in set (0.04 sec)表示只有2个数据库
+--------------+--------------------+----------------------------+------------------------+----------+
| catalog_name | schema_name | default_character_set_name | default_collation_name | sql_path |
+--------------+--------------------+----------------------------+------------------------+----------+
| def | information_schema | utf8 | utf8_general_ci | null |
| def | test | gb2312 | gb2312_chinese_ci | null |
+--------------+--------------------+----------------------------+------------------------+----------+
mysql> select * from information_schema.columns; #
# 关键的字段是table_name & column_name 411 rows in set (0.05 sec)
+---------------+--------------------+---------------------------------------+-------------------------------+------------------
| table_catalog | table_schema | table_name | column_name | ordinal_position | column_default | is_nullable | data_type |
character_maximum_length | character_octet_length | numeric_precision | numeric_scale | character_set_name | collation_name | column_type | column_key | extra
| privileges | column_comment |
+---------------+--------------------+---------------------------------------+-------------------------------+------------------ mysql> select * from information_schema.tables; # 包含所有的表名 ，38 rows in set (0.09 sec) 表示有38张表
mysql> select count(*) from information_schema.tables; # count(*)返回一共有多少行（就是多少条记录）
+----------+
| count(*) |
+----------+
| 38 |
+----------+
1 row in set (0.00 sec)
#关键的字段是table_column & table_name
+---------------+--------------------+---------------------------------------+-------------+--------+---------+------------+--
| table_catalog | table_schema | table_name | table_type | engine | version | row_format | table_rows | avg_row_length | data_length |
max_data_length | index_length | data_free | auto_increment | create_time | update_time | check_time | table_collation | checksum | create_options |
table_comment |
+---------------+--------------------+---------------------------------------+-------------+--------+---------+------------+--
mysql> select * from information_schema.tables where table_schema="test";
# 关键字是table_name和table_schema (数据库名)
+---------------+--------------+------------+------------+--------+---------+------------+------------+----------------+-----
| table_catalog | table_schema | table_name | table_type | engine | version | row_format | table_rows | avg_row_length | data_length | max_data_length | index_length |
data_free | auto_increment | create_time | update_time | check_time | table_collation | checksum | create_options | table_comment |
+---------------+--------------+------------+------------+--------+---------+------------+------------+----------------+-----
| def | test | t_users | base table | innodb | 10 | compact | 0 | 0 | 16384 | 0 | 16384 | 9437184 | 1 | 2012-10
-06 12:21:23 | null | null | gb2312_chinese_ci | null | | |
+---------------+--------------+------------+------------+--------+---------+------------+------------+----- |