程序媛计划——mysql 插入、查找、修改、删除数据

#插入、查找数据

[mysql>create table if not exists exam_score(
     ..>id int(4) not null primary key auto_increment,
     ..>name char(20) not null,
　　  ..>score double(6,2));

#用多个list插入多行数据 
[mysql> insert into exam_score values (1,'Zhao',95.33),(2,'Qian',94.33),(3,'Sun',44.55),(4,'Li',33.55);
Query OK, 4 rows affected (0.01 sec)
Records: 4  Duplicates: 0  Warnings: 0

#展示整张表
mysql> select * from exam_score;
+----+------+-------+
| id | name | score |
+----+------+-------+
|  1 | Zhao | 95.33 |
|  2 | Qian | 94.33 |
|  3 | Sun  | 44.55 |
|  4 | Li   | 33.55 |
+----+------+-------+
4 rows in set (0.00 sec)


mysql> insert into exam_score values (5,'Zhou',66.33),(6,'Wu',99.32),(7,'Zheng',33.2),(8,'Wang',99.3);
Query OK, 4 rows affected (0.00 sec)
Records: 4  Duplicates: 0  Warnings: 0

#查询按照字段id在0到2之间的行数据
mysql> select * from exam_score order by id limit 0,2;
+----+------+-------+
| id | name | score |
+----+------+-------+
|  1 | Zhao | 95.33 |
|  2 | Qian | 94.33 |
+----+------+-------+
2 rows in set (0.00 sec)

#查询整张表中的前两行
mysql> select * from exam_score limit 0,2;
+----+------+-------+
| id | name | score |
+----+------+-------+
|  1 | Zhao | 95.33 |
|  2 | Qian | 94.33 |
+----+------+-------+
2 rows in set (0.00 sec)

#按照name字段升序显示整张表
mysql> select * from exam_score order by name asc;
+----+-------+-------+
| id | name  | score |
+----+-------+-------+
|  4 | Li    | 33.55 |
|  2 | Qian  | 94.33 |
|  3 | Sun   | 44.55 |
|  8 | Wang  | 99.30 |
|  6 | Wu    | 99.32 |
|  1 | Zhao  | 95.33 |
|  7 | Zheng | 33.20 |
|  5 | Zhou  | 66.33 |
+----+-------+-------+
8 rows in set (0.01 sec)

#按照name降序显示
mysql> select * from exam_score order by name desc;
+----+-------+-------+
| id | name  | score |
+----+-------+-------+
|  5 | Zhou  | 66.33 |
|  7 | Zheng | 33.20 |
|  1 | Zhao  | 95.33 |
|  6 | Wu    | 99.32 |
|  8 | Wang  | 99.30 |
|  3 | Sun   | 44.55 |
|  2 | Qian  | 94.33 |
|  4 | Li    | 33.55 |
+----+-------+-------+
8 rows in set (0.00 sec)

#where条件查询 
mysql> select * from exam_score where name='Li';
+----+------+-------+
| id | name | score |
+----+------+-------+
|  4 | Li   | 33.55 |
+----+------+-------+
1 row in set (0.00 sec)

mysql> select * from exam_score where  id=3;
+----+------+-------+
| id | name | score |
+----+------+-------+
|  3 | Sun  | 44.55 |
+----+------+-------+
1 row in set (0.00 sec)

mysql> select * from exam_score where name='Zhao' and score<=99.0;
+----+------+-------+
| id | name | score |
+----+------+-------+
|  1 | Zhao | 95.33 |
+----+------+-------+
1 row in set (0.00 sec)

#修改数据

#连接表所在的数据库
mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select * from exam_score;
+----+-------+-------+
| id | name  | score |
+----+-------+-------+
|  1 | Zhao  | 95.33 |
|  2 | Qian  | 94.33 |
|  3 | Sun   | 44.55 |
|  4 | Li    | 33.55 |
|  5 | Zhou  | 66.33 |
|  6 | Wu    | 99.32 |
|  7 | Zheng | 33.20 |
|  8 | Wang  | 99.30 |
+----+-------+-------+
8 rows in set (0.00 sec)

#用update修改符合条件的字段的值

#通过条件定位到行，修改行的某些字段的值

#也可以修改多个字段的值，中间用逗号隔开

mysql> update exam_score set score =62.5 where name='Zheng' and score<60.0;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

#配合replace修改符合条件的字段的值

#replace(字段，旧值，新值)
mysql> update exam_score set name=replace(name,'Wu','Xie') where id=6;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from exam_score;
+----+-------+-------+
| id | name  | score |
+----+-------+-------+
|  1 | Zhao  | 95.33 |
|  2 | Qian  | 94.33 |
|  3 | Sun   | 44.55 |
|  4 | Li    | 33.55 |
|  5 | Zhou  | 66.33 |
|  6 | Xie   | 99.32 |
|  7 | Zheng | 62.50 |
|  8 | Wang  | 99.30 |
+----+-------+-------+
8 rows in set (0.00 sec)

删除记录／数据表

#删除表

mysql> delete from exam_score where id=4;
Query OK, 1 row affected (0.00 sec)

#delete清空整张表,表还在只是空了
mysql> delete from exam_score;
Query OK, 7 rows affected (0.00 sec)

mysql> select * from exam_score;

Empty set (0.00 sec)

#drop清空表

mysql> drop table exam_score;
Query OK, 0 rows affected (0.01 sec)

mysql> select * from exam_score;
ERROR 1146 (42S02): Table 'test.exam_score' doesn't exist