常用mysql查询语句

1.查看数据库连接数

  select * from information_schema.processlist where DB='pre_shove_netwin_gxb'

2.获取数据库的数据结构信息

SELECT

TABLE_NAME as '表名',

column_name AS '列名',
data_type AS '数据类型',
character_maximum_length AS '字符长度',
numeric_precision AS '数字长度',
numeric_scale AS '小数位数',
is_nullable AS '是否允许非空',
CASE WHEN extra = 'auto_increment'
THEN 1 ELSE 0 END AS '是否自增',
column_default AS '默认值',
column_comment AS '备注',
TABLE_SCHEMA as '数据库'
from information_schema.COLUMNS where TABLE_SCHEMA='robo'

order by TABLE_NAME asc

SELECT * from information_schema.COLUMNS
SHOW DATABASES