MySQL 查询自增id最大值
SELECT Auto_increment FROM information_schema.`TABLES` WHERE Table_Schema='smartinstall' AND table_name = 'upg_setting' limit 1;
MySQL 重置自增id为1
alter table tablename auto_increment=1
MySQL查询某个字段包含不同的值及各个不同值的个数
select column_name, count(1) as counts from table_name group by column_name;
MySQL查询某列包含A或B的所有记录
select * from table_name v where column_name = 'A' OR 'B'