简单sql语句大全（常用sql语句）

三张表 学生信息、 课程表、分数表

创表语句

-- 学生信息

create table t0_student

(

studentid varchar(10),

classid varchar(10),

name varchar(20),

sex varchar(1)

);

comment on column t0_student.studentid is '学生编码';

comment on column t0_student.classid is '学生班级 1 班级1 ，2 班级2';

comment on column t0_student.name is '学生姓名';

comment on column t0_student.sex is '学生性别,1 男，2 女';

alter table t0_student add constraint pk_t0_student primary key (studentid,classid)

-- 课程表

create table to_course

(

courseid varchar(10),

coursename varchar(10)

);

comment on column to_course.courseid is '课程编码，1,2,3,4,5';

comment on column to_course.coursename is '课程名称 1英语,2语文,3数学,4物理，5化学';

alter table to_course add constraint pk_to_course primary key (courseid);

-- 分数表

create table to_score

(

courseid varchar(10)，

classid varchar(10),

studentid varchar(10),

score number

);

comment on column to_score.courseid is '课程编码';

comment on column to_score.classid is '班级编码';

comment on column to_score.studentid is '学生编码';

comment on column to_score.score is '分数';

alter table to_score add constraint pk_to_score primary key (courseid,classid,studentid);

insert into t0_student values('1','1','张三','1');

insert into t0_student values('2','1','李四','2');

insert into t0_student values('3','1','王五','1');

insert into t0_student values('4','1','赵六','2');

insert into t0_student values('5','2','张三','1');

insert into t0_student values('6','2','李四','2');

insert into t0_student values('7','2','王五','1');

insert into t0_student values('8','2','赵六','2');

insert into t0_student values('9','1','jackMa','1');

insert into to_course values('1','英语');

insert into to_course values('2','语文');

insert into to_course values('3','数学');

insert into to_course values('4','物理');

insert into to_course values('5','化学');

insert into to_score values('1','1','1',50);

insert into to_score values('1','2','1',70);

insert into to_score values('2','1','2',100);

insert into to_score values('2','2','2',100);

insert into to_score values('3','1','3',90);

insert into to_score values('3','2','1',70);

insert into to_score values('4','1','4',80);

insert into to_score values('4','2','1',60);

insert into to_score values('5','1','4',90);

insert into to_score values('4','2','5',80);

insert into to_score values('3','2','5',80);

insert into to_score values('2','2','5',80);

insert into to_score values('1','2','5',80);

insert into to_score values('5','2','6',75);

insert into to_score values('4','2','6',60);

insert into to_score values('3','2','6',60);

insert into to_score values('2','2','6',60);

insert into to_score values('1','2','6',90);

/****************************************************************************sql 语句 ****************************************************************************/

--- 2班张三分数列表

select student.name, decode(student.sex,'1','男','2','女') sex,course.coursename,score.score

from to_score score, t0_student student, to_course course

where student.studentid='5' and student.classid='2'

and score.courseid = course.courseid

and student.studentid = score.studentid

and student.classid = score.classid

--- 2班 成绩行转列方式展示

with t as(

select student.name, decode(student.sex,'1','男','2','女') sex,course.coursename,score.score

from to_score score, t0_student student, to_course course

where score.courseid = course.courseid

and student.studentid = score.studentid

and student.classid = score.classid and student.classid='2' )

select * from(select * from t

)

pivot (sum(score) for coursename in ('英语','语文','数学','物理','化学'));

--- 查询分数大于80分 的人数

select count(distinct studentid) from to_score

where score>80

--查询有两科成绩大于 80分记录数

select studentid,score,count(*) from to_score

where score>=80

group by studentid,score

having count(*)>2

--- 查询所有的英语成绩 按成绩 由高往低排序

select * from to_score where courseid ='1' order by score desc

-- 查询 所有后英语成绩的总分，最高分，最低分,平均分（保留两位小数）

select sum(score) 总分,max(score) 最高分,min(score) 最低分,round(sum(score)/count(*),2) 平均分 from to_score where courseid ='1'

-- 查询所有成绩 优秀人数 (>=90)，良好人数(80-90)，及格人数(60-80)， 不及格人数(<60)

select suM(case

when score>=90 then 1

else 0 end ) 优秀人数,

suM( case

when score >=80 and score<90 then 1

when score >=60 and score<80 then 1

else 0 end) 良好人数,

suM(case

when score >=60 and score<80 then 1

else 0 end) 及格人数,

suM( case

when score <60 then 1

else 0 end) 不及格人数

from to_score

---查询90分以上各分数人数。rollup 统计总人次

select score ,count(*) from to_score where score >=90 group by rollup(score)

--- 删除名字重复的 学生 （如果没有studentid 这样的主键列的时候 可以通过rownum 增加一个虚拟列然后再删除）

delete t0_student

where studentid in(select studentid from (

select max(studentid) studentid ,name from t0_student group by name ))

--查询为非汉字的学生名字

select * from t0_student where asciistr(name) not like '%\%';

--随机抽取成绩中10% 数据

select * from to_score sample block(10);

,