创建表DDL 增删改DMLDQL查询操作

Posted 2021-12-01 abcdjava

1.创建一张Student表，创建表DDL 

 

 1 import static org.junit.Assert.*;
 2 
 3 import java.sql.Connection;
 4 import java.sql.DriverManager;
 5 import java.sql.Statement;
 6 
 7 import org.junit.Test;
 8 
 9 /**
10  * 创建一个学生表，
11  * SQL语句：create table t_student(id int prinmary key auto_increment,name varchar(20),age int)
12  * 
13 */
14 
15 public class DDLTest {
16     private static final String str = null;
17     
18     @Test
19     public void testCreateTable() throws Exception {
20         //贾琏欲执事，贾--加(贾)载注册驱动，琏--获取数据库连(琏)接对象 ，创建语(欲)句，执(执)行SQL语句，释(事)放资源(先开后关)
21         String sql = "create table t_student (id int primary key auto_increment,name varchar(50),age int)";
22         
23         //1.加载注册驱动
24         Class.forName("com.mysql.jdbc.Driver");
25         
26         //2.获取数据库连接对象
27         Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbcdemo", "root", "root");
28         
29         //3.创建语句
30         Statement st = conn.createStatement();
31         
32         //4.执行SQL语句
33         st.executeUpdate(sql);
34         
35         
36         //5.释放资源(先开后关)
37         st.close();
38         conn.close();
39     }
40     
41     
42 }

 

增删改DML：

 1 import static org.junit.Assert.*;
 2 
 3 import java.sql.Connection;
 4 import java.sql.DriverManager;
 5 import java.sql.Statement;
 6 
 7 import org.junit.Test;
 8 //插入数据 SQL:insert into t_student (name,age) values(‘小乔‘,30)
 9 public class DMLTest {
10     
11     
12     @Test
13     public void testInsert() throws Exception {
14         String sql = "insert into t_student (name, age) values(‘大桥‘,30)";
15         //贾琏欲执事
16         //1.加载注册驱动
17         Class.forName("com.mysql.jdbc.Driver");
18         
19         //2.获取数据库连接对象
20         Connection conne = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbcdemo", "root", "root");
21         
22         //3.创建语句
23         Statement St = conne.createStatement();
24         
25         //4.执行SQL语句
26         St.executeUpdate(sql);
27         
28         //5.释放空间(先开后关)
29         St.close();
30         conne.close();
31     }    
32         /*
33          * 
34          * 修改操作：update t_student set name = ‘貂蝉‘,age = 35 where id = 3
35          * 
36          * 
37          */
38         @Test
39         public void testUpdate() throws Exception {
40             String sql = "update t_student set name = ‘貂蝉‘,age = 35 where id =3";
41             //贾琏欲执事
42             //1.加载注册驱动
43             Class.forName("com.mysql.jdbc.Driver");
44             
45             //2.获取数据库连接对象
46             Connection conne = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbcdemo", "root", "root");
47             
48             //3.创建语句
49             Statement St = conne.createStatement();
50             
51             //4.执行SQL语句
52             St.executeUpdate(sql);
53             
54             //5.释放空间(先开后关)
55             St.close();
56             conne.close();
57         
58         
59     }
60         /*
61          * 删除数据SQL：delete from t_student where id = 4
62          * 
63          */
64         
65         @Test
66         public void testDelete() throws Exception {
67             String sql = "delete from t_student where id = 4";
68             //贾琏欲执事
69             //1.加载注册驱动
70             Class.forName("com.mysql.jdbc.Driver");
71             
72             //2.获取数据库连接对象
73             Connection conne = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbcdemo", "root", "root");
74             
75             //3.创建语句
76             Statement St = conne.createStatement();
77             
78             //4.执行SQL语句
79             St.executeUpdate(sql);
80             
81             //5.释放空间(先开后关)
82             St.close();
83             conne.close();
84         
85         
86     }
87     
88 }

 

 

 

DQL查询操作