简单SQL语句

1、说明：几个简单的基本的sql语句

选择：select * from table1 where 范围
插入：insert into table1(field1,field2) values(value1,value2)
删除：delete from table1 where 范围
更新：update table1 set field1=value1 where 范围
查找：select * from table1 where field1 like ’%value1%’ ---like的语法很精妙，查资料!
排序：select * from table1 order by field1,field2 [desc]
总数：select count as totalcount from table1
求和：select sum(field1) as sumvalue from table1
平均：select avg(field1) as avgvalue from table1
最大：select max(field1) as maxvalue from table1
最小：select min(field1) as minvalue from table1


MySQL中

SELECT CONCAT('update ',table_schema,".",table_name," set schoolId=149;") FROM `information_schema`.columns WHERE table_schema='idsp_jn14' AND column_name='schoolId'

在MySQL中执行完如下

update idsp_jn14.bas_classroom set schoolId=149;

conca()是MySQL中的字符串拼接函数

`information_schema`.columns 是信息数据库，其中保存着关于MySQL服务器所维护的所有其他数据库的信息