MySQL小知识：查看mysql数据库 服务器信息命令集

– 查询MySQL版本

select version() from dual;

– 查看数据库字符串拼接长度

show variables like 'group_concat_max_len';

– 显示MySQL最大连接数

show variables like '%max_connections%';

– 修改最大连接数

-- set GLOBAL max_connections = 200;

– 服务器响应的MySQL最大连接数—比较理想的设置是： Max_used_connections /

max_connections * 100% ≈ 85% 　　
show status like '%connections%';

– 查看MySQL线程

show status like '%Threads%';

– mysql中查看索引占用的存储空间使用下面的sql语句

SELECT
table_name,
concat( TRUNCATE ( data_length / 1024 / 1024, 2 ), 'MB' ) AS data_size,
concat( TRUNCATE ( index_length / 1024 / 1024, 2 ), 'MB' ) AS index_size 
FROM
information_schema.TABLES 
WHERE
	table_name = 'ec_order' 
ORDER BY
index_size DESC;

– 查看单个表的细分索引情况：

select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,CARDINALITY from 
information_schema.STATISTICS 	iss
where iss.table_name='ec_order';

– 查询表及索引占用空间

select * from information_schema.TABLES
where information_schema.TABLES.TABLE_SCHEMA='ftms_union' and 	
information_schema.TABLES.TABLE_NAME='ec_order'

– 查询Sql模板

select @@global.sql_mode