[数据库] SQL语句select简单记录总结

--创建数据库
create database StudentMS

--使用数据库
use StudentMS

--删除数据库
--drop database StudentMS

--创建学生表 (属性:姓名、学号(pk)、学院、出生日期、性别、籍贯)
create table xs
(
	name varchar(10) not null,
	id varchar(10) not null,
	xy varchar(10),
	birthday datetime,
	xb char(2),
	jg varchar(8)
)

--创建学生表主键:学号
alter table xs
	add constraint
pk_xs primary key(id)


--创建表学生表外键:系代号 此表中xdh已被省略
alter table xs
	add constraint
fk_xs foreign key(xdh)
references xb (xdh)

insert into xs 
	(id, name, xb, birthday, xy, jg) 
values('1160001', '刘备', '男', '1991-11-5', '软件学院', '河北省'); 

select id as 学号, name as 姓名, year(getdate())-year(birthday) as 年龄, birthday as 出生日期
from xs;

select id as 学号, name as 姓名, datediff(YY,birthday,getdate()) as 年龄, birthday as 出生日期
from xs;

--方法1：group by 列分组
select xy from xs group by xy;

--方法2：列出不同的值
select distinct xy from xs;

--匹配姓名以"黄"开头的学生
select * from xs where name like '黄%';

--匹配学院包含"计算机"的学生
select * from xs where xy like '%计算机%';

--匹配姓名以"尚香"结尾的学生
select * from xs where name like '%尚香';

select T_WSTB_DLPYJBQKB.DL_BHXNZYMC, ZY_NAME 
from T_WSTB_ZYJBQK, T_WSTB_DLPYJBQKB 
where T_WSTB_DLPYJBQKB.DL_BHXNZYMC like '%' || ZY_NAME ||'%'

select * from xs where jg in ('河北省','河南省');

select xy as 学院名称 from xs where xy='软件学院' group by xy;

--子查询统计人数
select a.a_num as 软院人数, b.b_num as 计院人数, c.c_num as 自动化人数, 
       d.d_num as 男生人数, e.e_num as 女生人数, f.f_num as 河北河南人数
from
(select count(*) as a_num from xs where xy='软件学院') a,
(select count(*) as b_num from xs where xy='计算机学院') b,
(select count(*) as c_num from xs where xy='自动化学院') c,
(select count(*) as d_num from xs where xb='男') d,
(select count(*) as e_num from xs where xb='女') e,
(select count(*) as f_num from xs where jg in ('河北省','河南省')) f;

--创建学院表 
create table table_xy
(
	name varchar(10) not null,
	id varchar(10) not null
);

--插入数据
insert into table_xy(id, name) values('001', '软件学院');
insert into table_xy(id, name) values('002', '计算机学院');
insert into table_xy(id, name) values('003', '自动化学院');
insert into table_xy(id, name) values('004', '法学院');

select distinct name as 学院名称, 
(select count(*) from xs where xs.xy=table_xy.name) as 总人数,
(select count(*) from xs where xs.xy=table_xy.name and xs.xb='男') as 男生总数,
(select count(*) from xs where xs.xy=table_xy.name and datediff(YY,birthday,getdate())<=25) as 二十五岁人数,
(select count(*) from xs where  xs.xy=table_xy.name and xs.jg in ('河北省','河南省'))　as 河北河南生源地
from table_xy;

select t1.ZFJGSL as 数量,
		trunc( 1.0 * (select ITEM_VALUE from T_WSTB_YJBKBYSJYQK
			where RECORD_YEAR=(to_char(sysdate, 'yyyy')-2) and FIRST_NUM='2' and SECOND_NUM='2') /
			(select ITEM_VALUE from T_WSTB_YJBKBYSJYQK
			where RECORD_YEAR=(to_char(sysdate, 'yyyy')-2) and FIRST_NUM='2' and SECOND_NUM='1') * 100,
		2) as 比例
from 
(select ITEM_VALUE as ZFJGSL from T_WSTB_YJBKBYSJYQK
 where RECORD_YEAR=(to_char(sysdate, 'yyyy')-2) and FIRST_NUM='2' and SECOND_NUM='2') t1;

select DL_NAME as num1,
	length(DL_BHXNZYMC)-length(replace(DL_BHXNZYMC,'，',''))+1 as num2
from T_WSTB_DLPYJBQKB

三. 总结