摘要： mybatis代码:<where> info.datastatus != 3 <if test="_parameter.containsKey('province')"> and geo.provinceName=#{province} </if> <if test="_parameter.cont 阅读全文

摘要： desc user; show index from user; user表id字段是主键,number,name,area_id是三个普通索引 explain-id: explain select id from (select * from user limit 10) alias; id相同时 阅读全文