一、添加数据
在添加新记录之前需要先创建一个数据库itcast，创建数据库的SQL语句如下所示：
mysql> CREATE DATABASE itcast;Query OK, 1 row affected
选择使用数据库itcast，SQL语句如下：
mysql> USE itcast;
Database changed
在数据库中创建一个表student1_tb用于存储学生信息，创建student_tb表的SQL语句如下所示：
mysql> CREATE TABLE student1_tb
-> (
-> id INT(20) PRIMARY KEY,
-> name VARCHAR(20) NOT NULL,
-> sex VARCHAR(10) UNIQUE,
-> grade FLOAT
-> );
Query OK, 0 rows affected
查看student1_tb中的内容
mysql> DESCRIBE student1_tb;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(20) | NO | PRI | NULL | |
| name | varchar(20) | NO | | NULL | |
| sex | varchar(10) | YES | UNI | NULL | |
| grade | float | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
4 rows in set
使用INSERT语句向student_tb表中插入一条数据，SQL语句如下所示：
mysql> INSERT INTO student1_tb(id,name,sex,grade) VALUES(1,"明","女",85);
Query OK, 1 row affected
当上述SQL语句执行成功后，会在表student1_tb中添加一条数据。为了验证数据是否添加成功，使用SELECT语句查看student_tb表中的数据，查询结果如下：
mysql> SELECT * FROM student1_tb;
+----+------+-----+-------+
| id | name | sex | grade |
+----+------+-----+-------+
| 1 | 明 | 女 | 85 |
+----+------+-----+-------+
1 row in set
继续为student1_tb添加数据；
mysql> INSERT INTO student1_tb(id,name,sex,grade) VALUES(2,"天","男",80);
Query OK, 1 row affected
mysql> INSERT INTO student1_tb(id,name,sex,grade) VALUES(3,"会","F",90);
Query OK, 1 row affected
同时添加多条记录；
mysql> INSERT INTO student1_tb VALUES(4,"更","M",70),(5,"好","N",60);
Query OK, 2 rows affected
Records: 2 Duplicates: 0 Warnings: 0
mysql> INSERT INTO student1_tb VALUES(6,"的","A",75),(7,"好","V",65);
Query OK, 2 rows affected
Records: 2 Duplicates: 0 Warnings: 0
执行成功后，验证是否添加成功；
mysql> SELECT * FROM student1_tb;
+----+------+-----+-------+
| id | name | sex | grade |
+----+------+-----+-------+
| 1 | 明 | 女 | 85 |
| 2 | 天 | 男 | 80 |
| 3 | 会 | F | 90 |
| 4 | 更 | M | 70 |
| 5 | 好 | N | 60 |
| 6 | 的 | A | 75 |
| 7 | 好 | V | 65 |
+----+------+-----+-------+
7 rows in set
二、更新数据
UPDATE更新部分数据
mysql> UPDATE student1_tb set name="哦",grade=95 WHERE id=7;
Query OK, 1 row affected
Rows matched: 1 Changed: 1 Warnings: 0
查看+验证：
mysql> SELECT * FROM student1_tb;
+----+------+-----+-------+
| id | name | sex | grade |
+----+------+-----+-------+
| 1 | 明 | 女 | 85 |
| 2 | 天 | 男 | 80 |
| 3 | 会 | F | 90 |
| 4 | 更 | M | 70 |
| 5 | 好 | N | 60 |
| 6 | 的 | A | 75 |
| 7 | 哦 | V | 95 |
+----+------+-----+-------+
7 rows in set
更新student1_tb表中id字段值小于4的记录，将这些记录的grade字段值都更新为100。
mysql> UPDATE student1_tb set grade=100 WHERE id<4;
Query OK, 2 rows affected
Rows matched: 3 Changed: 2 Warnings: 0
查看+验证：
mysql> SELECT * FROM student1_tb;
+----+------+-----+-------+
| id | name | sex | grade |
+----+------+-----+-------+
| 1 | 明 | 女 | 100 |
| 2 | 天 | 男 | 100 |
| 3 | 会 | F | 100 |
| 4 | 更 | M | 70 |
| 5 | 好 | N | 60 |
| 6 | 的 | A | 75 |
| 7 | 哦 | V | 95 |
+----+------+-----+-------+
7 rows in set
更新student1_tb表中id字段值小于4的记录，将grade字段值都更新为80。
mysql> UPDATE student1_tb set grade=80;
Query OK, 7 rows affected
Rows matched: 7 Changed: 7 Warnings: 0
查看+验证：
mysql> SELECT * FROM student1_tb;
+----+------+-----+-------+
| id | name | sex | grade |
+----+------+-----+-------+
| 1 | 明 | 女 | 80 |
| 2 | 天 | 男 | 80 |
| 3 | 会 | F | 80 |
| 4 | 更 | M | 80 |
| 5 | 好 | N | 80 |
| 6 | 的 | A | 80 |
| 7 | 哦 | V | 80 |
+----+------+-----+-------+
7 rows in set
三、删除数据
在student1_tb表中，删除id字段值为6的记录：
mysql> DELETE FROM student1_tb WHERE id=6;
Query OK, 1 row affected
查看+验证：
mysql> SELECT * FROM student1_tb;
+----+------+-----+-------+
| id | name | sex | grade |
+----+------+-----+-------+
| 1 | 明 | 女 | 80 |
| 2 | 天 | 男 | 80 |
| 3 | 会 | F | 80 |
| 4 | 更 | M | 80 |
| 5 | 好 | N | 80 |
| 7 | 哦 | V | 80 |
+----+------+-----+-------+
6 rows in set
在student1_tb表中，删除id字段值大于3的记录：
mysql> DELETE FROM student1_tb WHERE id>3;
Query OK, 3 rows affected
查看+验证：
mysql> SELECT * FROM student1_tb;
+----+------+-----+-------+
| id | name | sex | grade |
+----+------+-----+-------+
| 1 | 明 | 女 | 80 |
| 2 | 天 | 男 | 80 |
| 3 | 会 | F | 80 |
+----+------+-----+-------+
3 rows in set
DELETE删除全部数据
mysql> DELETE FROM student1_tb;
Query OK, 3 rows affected
执行DELETE语句删除student1_tb表中的数据，然后再次通过查询语句查看student1_tb表中的记录，执行结果如下所示：
mysql> SELECT * FROM student1_tb;
Empty set
从查询结果可以看到记录为空，说明表中所有的记录成功删除。