20190301转载数据库表操作

//登录和退出数据库
1：mysql -u root -p//输入密码
2: exit
3: mysql -u root -p

//数据库创建，删除，进入数据库
4：CREATE DATABASE `testdatabase`;
5: CREATE DATABASE `testdatabase`;
6：DROP DATABASE `testdatabase`;
7: CREATE DATABASE `testdatabase`;
8: USE testdatabase;
9: CREATE DATABASE `testdatabase2`;
10: USE DATABASE testdatabase2;
11: USE `testdatabase2`;
12: USE `testdatabase`;
13: DROP DATABASE `testdatabase2`;

//表的创建和删除，创建表同时设置属性
14: CREATE TABLE table1;
15: CREATE TABLE table1(No INT);
16: CREATE TABLE table2 (No INT,name VARCHAR(20),sex boolean);
17: DROP TABLE table1,table2;
18: CREATE TABLE tt1 (id INT(11) primary key);
19: CREATE TABLE tt2 (id int primary key, name varchar(20) unique, age int not null, sex boolean default '1');
//boolean 实际上是一个int，因此值为0或1
20：CREATE TABLE tt3 (id int primary key, age int not null auto_increment);
21: CREATE TABLE tt3 (id int primary key auto_increment, age int not null);
//一个表只能有一个auto_increment约束，且约束的属性必须是主键或主键的一部分
22：show tables;
23：drop table tt1,tt2,tt3;show tables;

//key键：
//主键：
24：create table tt1 (id int primary key);
25: create table tt2 (id int,name varchar(20),primary key (id));
26: create table tt3 (id int,name varchar(20),age int,primary key(id,name));
27: create table tt4(id int primary key,age int primary key);//只可以有一个主键
28: drop table tt1,tt2,tt3,tt4;

//外键：
29: create table tt1(id int(4),uid int(4));
30: create table tt2(id int(4),uid int(4),constraint nickname foreign key(uid) references tt1(uid));
31: drop table tt1;
create table tt1(id int,uid int,primary key(id,uid));
32: create table tt2(id int,uid int,constraint nickname foreign key(uid) references tt1(id));
//由上四条可知外键必须依赖于父表的主键上
33：create table tt2(id int(4),uid int(4),constraint nickname foreign key(uid) references tt1(id));
//外键连接必须连接的是主表的主键，如果连接主表主键的一部分，必须连接主键的第一个字段
34: create table tt3(id int,uid int,constraint nick name foreign key(id) references tt1(id));
35: drop table tt1,tt2,tt3;//此处会报错，因为有外键依赖要先删子表才能删父表，如果输入drop table tt3,tt2,tt1;则不会报错

36: create table tt1(Id int unsigned,uid int,primary key(id));
37: create table tt2(id int,uid int,constraint nickname foreign key (uid) references tt1(id));
38: create table tt2(id int,uid int unsigned,constraint foreign key (uid) references tt1(id));
//外键关联的主从表字段数据类型必须完全一样，否则报错“foreign key constraint is incorrectly formed”

//查看表：
39：describe tt1;
describe tt2;
40: desc tt1;
desc tt2;
41: show create table tt1;
show create table tt2;
42: show create table tt1 \G
show create table tt2 \G

//修改表：
//修改表名
43：alter table tt1 rename tt2;
44: alter table tt1 rename temp;
45: desc tt1;
desc temp;
46: alter table temp rename to tt1;
47: drop table tt1,tt2;

//修改表属性数据类型
48: create table tt1(id int,name varchar(20));
49: alter table tt1 modify id varchar(20);
50: insert into tt2(id,name) values(1,'string');//插入和删除操作还没有涉及，在这里只是为了加入一条数据已说明下面的问题
51：alter table tt1 modify name int;//有值的情况下转换字段类型失败，因为字符串类型无法自动转型为整数类型
52：delete from tt1；//删除表中元素
53: alter table tt1 modify name int;
desc tt1;

//修改表属性
54：alter table tt1 change name newname int;
desc tt1;
55: alter table tt2 change newname name varchar(20);
desc tt2;

//增加字段
56: alter table tt1 add name tinytext after id;
desc tt1;
57: alter table tt1 add age int not null after id;desc tt1;
58: alter table tt1 add no int unique first;desc tt1;

//删除字段
59：alter table tt1 drop age;desc tt1;desc tt1;

//修改属性排列顺序
60：alter table tt1 modify no int after name;desc tt1;
61: alter table tt1 modify no int first;desc tt1;
62: drop table tt1,tt2;

//索引：
//创建带索引的数据库表
63：create table tt1(id int,name varchar(20),age int,index index1(id));
64: show create table tt1\G
65: explain select * from tt1 where id=1;//explain语句用来查看索引详细情况，参考博文：http://blog.csdn.net/zhuxineli/article/details/14455029
66：create table tt2(id int,name varchar(20),age int,unique index index2(id));//唯一索引，唯一索引指的是被索引的字段值唯一
67: show create table tt2\G
68: create table tt3(id int,name varchar(20),age int,fulltext index index3(id));//全文索引
69: create table tt3(id int,name varchar(20),age int,fulltext index index3(name));
70: show create table tt3\G
71: create table tt4(id int,age int,info varchar(50),index index4(info(10)));
72: show create table tt4\G
73: create table tt5(id int,name varchar(20),info varchar(50),index index5 (id,name));
74: show create table tt5\G
75: explain select * from tt5 where name="nnn"\G
76: explain select * from tt5 where id='1'\G

//在已存在表上添加索引
//create [unique|fulltext|spatial] index indexname on tablename (columnname [(length)] [ASC|DESC]);

77: drop database testdatabase;
create database testdatabase;
use testdatabase;
78: create table tt1(id int,name varchar(20));
79: create index index1 on tt1 (id);
80: create index index1 on tt1 (name);//同一表的索引别名不能相同
81: create index index2 on tt1 (name);
82: drop index index2 on tt1;
83: create table tt2(id int,name varchar(20),age int,sex boolean,info varchar(50));
84: create index index1 on tt2 (id);//不同表的索引别名可以相同
85：create unique index index2 on tt2 (id);//不同索引可以重复使用相同字段
86: create fulltext index index3 on tt2 (name);
87: create index index4 on tt2 (sex,age);//多字段索引
88：show create table tt2;
89: drop table tt1,tt2;
90: show tables;

//Alter语句添加索引
//Alter table tablename add [unique|fulltext|spatial] index indexname (columename [(length)] [ASC|DESC]);
91: create table tt1(id int);
92: alter table tt1 add index index1 (id);
93: create table tt2 (id int,age int,name varchar(20),sex boolean, info varchar(50));
94：alter table tt2 add index index2 (id,name);
95: alter table tt2 add unique index index3 (sex);
96: alter table tt2 add index index4 (info(10));
97: alter table tt2 add fulltext index index5 (info(10));
show create table tt2;

//删除索引
98: drop index index1 on tt2;
show create table tt2;//观察删除索引后的表信息
99：drop table tt1,tt2;
100: exit
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作者：WayBling
来源：CSDN
原文：https://blog.csdn.net/picway/article/details/53646994

//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]";
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作者：WayBling
来源：CSDN
原文：https://blog.csdn.net/picway/article/details/53822440