mysql 入门练习(2)

//重建数据库

101, create database testdatabase;use database testdatabase;

102, create table tt1(id int, name varchar(20),age int,sex boolean);

103, show tables;desc tt1;

//插入

104, insert into tt1 values(1,"zhang",25,0);

105, insert into tt1 values(2,"wang",25,1);

106, select * from tt1;

107, insert into tt1(id,name,age,sex) values(3,"li",28,1);

108, insert into tt1(id,name,sex,age) values(4,"sun",0,22);

109, insert into tt1(id,name,sex) values(5,"zhao",30,1);

110, insert into tt1(id,age,name) values(6,"he",47,0);

111, insert into tt1(id,age,name) values(7,"chen",22,1),(7,"zhang",22,1),(7,"xie",32,1);

112, select * from tt1;

//修改

113, update tt1 set id=10,name="new",age=100,sex=0 where id=1; select * from tt1;

114, update tt1 set id=11,name="new" where id=2,age=25; select *from tt1;

115, update tt1 set id=12,sex=1 where id=7; select * from tt1;

116, update tt1 set sex=1 where id>3;

117, update tt1 set sex=0 where id<4;

//删除

118, delete from tt1 where id=1;select * from tt1;

119, delete from tt1 where id=12;select * from tt1;

//查询

120, alter table tt1 add address varchar(30);

121, update tt1 set address="Beijing" where sex=1;

122, update tt1 set address="Shanghai" where sex=0;

//简单查询

123, select id from tt1;

124, select id,name from tt1;

125, select id,name,address from tt1;

//条件查询

126, select id,name,address from tt1 where address="Beijing";

127, select * from tt1 where id in(2,3,4);

128, select * from tt1 where id not in(2,3,4);

129, select * from tt1 where id between 2 and 5;

130, select * from tt1 where id not between 2 and 5;

131, select * from tt1 where address like "beijing";

132, select * from tt1 where address like "bei";

133, select * from tt1 where address like "bei%";

134, select * from tt1 where address not like "bei%";

135, select * from tt1 where address is null;

136, select * from tt1 where address is not null;

137, select * from tt1 where age<20 and sex=1;

138, select * from tt1 where sex=0 or age>30;

//查询结果不重复

139, select distinct address from tt1; 

//查询结果排序

140, select * from tt1 order by age;

141, select * from tt1 order by age asc;

142, select * from tt1 order by age desc;

//分组查询

143, select * from tt1 group by sex;/

/单独使用group by 只会选择每个分组的一条记录

//group by 与 group_concat结合使用

144, select group_concat(name),sex from tt1 group by sex;

145, select group_concat(name),group_concat(age),sex from tt1 group by sex;

146, select group_concat(name,age),sex from tt1 group by sex;

//group by与集合函数结合使用

147, select sex,count(sex) from tt1 group by sex;

148, select sex,count(sex) from tt1 group by sex having sex>2;//having用于对分组后的结果加限制条件

149, select sex,count(sex) from tt1 group by sex having count(sex)>2;

//with rollup

150, select sex,count(sex) from tt1 group by sex with rollup

;//在显示记录的最后一行加一条，记录是上面所有记录的和，通常用于合计数量
//limit显示限制

151, select * from tt1;

152, select * from tt1 limit 2;

153, select * from tt1 limit 3;

154, select * from tt1 limit 0,2;

155, select * from tt1 limit 1,2;

//使用集合函数查询

//为了更好的理解本问题，新建一个表

156, create table grade(id int,name varchar(10),subject varchar(10),score int,sex boolean);

157, insert into grade values(1,"wang","math",100,1),(1,"wang","english",96,1),(1,"wang","physics",90,1);

insert into grade values(2,"li","math",96,1),(2,"li","english",85,1),(2,"li","physics",99,1);

insert into grade values(3,"sun","math",85,0),(3,"sun","english",98,0),(3,"sun","physics",80,0);

158, select * from grade;

159, select count(*) from grade;

160, select id,name,sum(score) from grade where id=1;

161, select id,name,sun(score) from grade group by id;

162, select id,name,sum(score) from grade group by id order by sum(score) desc;

163, select id,name,avg(score) from grade where id=2;

164, select id,name,avg(score),sum(score) from grade where id =3;

165, select id,name,avg(score) from grade group by id;

166, select subject,avg(score) from grade group by subject;* from 

167, select subject,avg(score) from grade group by subject order by avg(score);

168, select name,max(score) from grade where subject="math";

169, select name,max(score) from grade where subject="english";

//连接查询

//内连接

170, create table stu(id int,name varchar(10),age int,sex boolean);

171, insert into stu values(1,"wang",25,1),(2,"li",23,1),(3,"sun",23,0),(4,"zhou",27,1),(5,"zhang",22,0);

172, select id,name,age,sex,score from stu,grade where stu.id=grade.id;

173, select stu.id,stu.name,stu.age,stu.sex,score from stu,grade where stu.id=grade.id;

174, select stu.id,stu.name,stu.age,stu.sex,score from stu,grade where stu.id=grade.id and score>90;

 

//外连接

175, select stu.id,stu.name,stu.age,stu.sex,score from stu left join grade on stu.id=grade.id;

176, select stu.id,stu.name,stu.age,stu,sex,score from stu right join grade on stu.id=grade.id;

177, insert into grade values(4,"hu","math",99,1),(5,"liu","english",97,0);

178, select stu.id,stu.name,stu.age,stu.sex,subject,score from stu left join grade on stu.id=grade.id;

179, select stu.id,stu.name,stu.age,stu.sex,subject,score from stu right join grade on stu.id=grade.id;

//子查询

180, select * from stu where id in (select *from grade);

181, select * from grade where id in (select * from stu);

182, create table scholarship(level int,money int,score int);

183, insert into scholarship values(1,10000,90),(2,5000,85),(3,3000,80);

184, select id,name,score from grade where score>=(select score from scholarship where level=1);

185, select id,name,score from grade where score>=(select min(score) from scholarship);

//exists子查询

186, select * from stu where exists (select name from grade where id=1);

187, select * from grade where score>any(select score from scholarship);

188, select * from grade where score>all(select score from scholarship);

//合并查询结果

189, select name from stu union select name from grade;

190, select name from stu union all select name from grade;

//别名

191, select * from scholarship s where s.level=1;

192, select * from scholarship s where s.money=5000;

193, select s.name from stu s,grade g where s.name=g.name;

194, select subject as su,score as sc from grade;

195, select * from stu where name regexp "^w";

196, select * from stu where name regexp "g$";

197, select * from stu where name regexp "^w.g$";
198, select * from stu where name regexp "^w..g$";
199, select * from stu where name regexp "[aeo]";
200, select * from stu where name regexp "[a-g]";