MySQL高级SQL语句
1.MySQL进阶查询
数据库实例准备:
create database kgc;
use kgc;
###在数据库kgc中创建数据表location,并添加数据记录
create table location (Region char(20),Store_Name char(20));
insert into location values('East','Boston');
insert into location values('East','New York');
insert into location values('West','Los Angeles');
insert into location values('West','Houston');
###在数据库kgc中创建数据表store_info,并添加数据记录
create table store_info (Store_Name char(20),Sales int(10),Date char(10));
insert into store_info values('Los Angeles','1500','2020-12-05');
insert into store_info values('Houston','250','2020-12-07');
insert into store_info values('Los Angeles','300','2020-12-08');
insert into store_info values('Boston','700','2020-12-08');
1.1 select
select:显示表格中一个或数个字段的所有数据记录
语法:SELECT "字段" FROM "表名";
select store_name from store_info;
1.2 distinct
distinct:不显示重复的数据记录
语法:SELECT DISTINCT "字段" FROM "表名";
select distinct store_name from store_info;
1.3 where
where:有条件查询
语法:SELECT "字段" FROM "表名" WHERE "条件";
select * from store_info where sales > 1000;
1.4 and or
and or:且 或
语法:SELECT "字段" FROM "表名" WHERE "条件1" {
[AND|OR] "条件2"}+ ;
select * from store_info where sales > 1000 or (sales >=200 and sales <=500);
1.5 in
in:显示已知的值的数据记录
语法:SELECT "字段" FROM "表名" WHERE "字段" IN ('值1'