iteye_20286的博客

explain使用： explain select * from e3_eval_domain_cn where srcId <1000   創建索引： create index index_name on table_name(column1，column2 ...);   刪除索引： drop index index_name on table_name ; ...

基础知识： 创建表：create table A (........); 查询记录：select * from A 更新记录：update A set a.x=y where a.z=c 插入记录: insert into A(x,y,z) values(......); 删除某记录:delete [form] A where a.x =y [如果删除整表数据则...

update table[表名] set Fields[字段名]=replace(Fields[字段名],'被替换原容','要替换 成的内容') 如: admin@hcmcms 方法一： update useraccount set userName = replace(userName,'@hcmcms','@aa'); 方法二： update useraccoun...

select count(*) from ( select studentId as stuId, avg(score) as avgScore from evalResult where classId = 266 and evalItemType like '%認知發展→%' group by studentId ) er where er.avgScore >3 and er.avg...