mysql表结构表空间和索引的查询_MySQL

mysql表结构表空间和索引的查询

1.查询表的结构信息

Sql代码

desc tableName;

show columns from tableName;

describe tableName

上面的结果返回的结果是一样的。

2 查询表的列信息。

Sql代码

select * from

information_schema.columns

where table_name='tableName';

3 查看库中所有的库

Sql代码

SELECT LOWER(schema_name) schema_name

FROM

information_schema.schemata

WHERE

schema_name NOT IN (

'mysql',

'information_schema',

'test'

)

4 查询某个库中所有的表

Sql代码

SELECT table_name, create_time updated_at, table_type, ENGINE, table_rows num_rows, table_comment, CEIL(data_length / 1024 / 1024) store_capacity

FROM

information_schema.TABLES

WHERE table_schema = 'schema_name' AND table_name NOT LIKE 'tmp#_%' ESCAPE '#'

5 查看某一个库下某一个表的所有字段

Sql代码

SELECT

lower(column_name) column_name,

ordinal_position position,

column_default dafault_value,

substring(is_nullable, 1, 1) nullable,

column_type data_type,

column_comment,

character_maximum_length data_length,

numeric_precision data_precision,

numeric_scale data_scale

FROM

information_schema.COLUMNS

WHERE

table_schema = 'admin_portal'

AND table_name = 'ap_epiboly_task';

6 查看某一个库下某一张表的索引

Sql代码

SELECT DISTINCT

lower(index_name) index_name,

lower(index_type) type

FROM

information_schema.statistics

WHERE

table_schema = 'employees'

AND table_name = 'employees';

7 查看某一个库下某一个表的注释

Sql代码

SELECT

table_comment comments

FROM

information_schema.TABLES

WHERE

table_schema = 'employees'

AND table_name = 'employees';

8

1.查看索引

（1）单位是GB

SELECT CONCAT(ROUND(SUM(index_length)/(1024*1024*1024), 2), ' GB') AS 'Total Index Size' FROM information_schema.TABLES WHERE table_schema LIKE 'test';

+------------------+

| Total Index Size |

+------------------+

| 1.70 GB |

+------------------+

（2）单位是MB

SELECT CONCAT(ROUND(SUM(index_length)/(1024*1024), 2), ' MB') AS 'Total Index Size' FROM information_schema.TABLES WHERE table_schema LIKE 'test';

其中“database”为你所要查看的数据库

2.查看表空间

SELECT CONCAT(ROUND(SUM(data_length)/(1024*1024*1024), 2), ' GB') AS 'Total Data Size'

FROM information_schema.TABLES WHERE table_schema LIKE 'test';

+-----------------+

| Total Data Size |

+-----------------+

| 3.01 GB |

+-----------------+

3.查看数据库中所有表的信息

SELECT CONCAT(table_schema,'.',table_name) AS 'Table Name',

CONCAT(ROUND(table_rows/1000000,2),'M') AS 'Number of Rows',

CONCAT(ROUND(data_length/(1024*1024*1024),2),'G') AS 'Data Size',

CONCAT(ROUND(index_length/(1024*1024*1024),2),'G') AS 'Index Size' ,

CONCAT(ROUND((data_length+index_length)/(1024*1024*1024),2),'G') AS'Total'FROM information_schema.TABLES WHERE table_schema LIKE 'test';