mysql常用语句
查看各个数据库占用大小
select TABLE_SCHEMA, concat(truncate(sum(data_length)/1024/1024,2),’ MB’) as data_size,
concat(truncate(sum(index_length)/1024/1024,2),’MB’) as index_size
from information_schema.tables
group by TABLE_SCHEMA
order by data_length desc;
查看单个数据库各个表的大小
SELECT table_name, data_length + index_length AS len, table_rows,
CONCAT(ROUND((data_length + index_length)/1024/1024,2),’MB’) AS datas
FROM information_schema.tables
WHERE table_schema = ‘库名’
ORDER BY len DESC;
#统计表内字段值出现的次数
SELECT
字段名, COUNT(字段名)
FROM
表名 where 条件
GROUP BY
字段名
HAVING
(COUNT(字段名) > 出现多少次) ORDER BY COUNT(字段名) DESC
mysql设置信息
show variables like ‘%connect%’;
连接池信息
show global status like ‘Max_used_connections’;
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