mysql 查询语句

查询库下面的表的文件大小已mysql库为例
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_SCHEMA = 'mysql'
group by TABLE_NAME
order by data_length desc;

统计mysql 重复数据已name字段为例
select name ,count() as count from zipkin_spans group by name having count >1;
统计mysql表的数据总数
select count（） from zipkin_spans；

查看mysql前10条数据
select from tablename limit 10；
mysql字段模糊查询name字段
select from tablename where name like ‘%zhang’;
模糊查询统计数
select count（name） tablename where name like ‘%zhang’；
查看建表语句表明si
show create table si;