1.增

编写向数据库表增加一条记录的测试类代码（AddDemo1）

代码

package test1;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
 
public class AddDemo {
private static Statement statement;
private static Statement createStatement;
 
public static void main(String[] args) throws ClassNotFoundException, SQLException {
    // 1、加载驱动
    Class.forName("com.mysql.cj.jdbc.Driver");// 反射技术，保证内存中只有一个Driver对象
    // 2、创建连接
    String url="jdbc:mysql://localhost:3306/jdbc?serverTimezone=GMT%2B8&characterEncoding=utf8&useSSL=true";
    String user="root";// 数据库用户名
    String pw="123456";// 数据库密码(每个人都不一样我的是123456)
    Connection conn=DriverManager.getConnection(url, user, pw);//补全快捷键ctrl+1
    System.out.println(conn);//测试是否连接上mysql数据库
    // 3、得到执行sql语句的对象
    java.sql.Statement statement = conn.createStatement();//补全快捷键ctrl+1
    // 4、执行sql语句，并返回结果
    String sql="INSERT INTO student VALUES(NULL,'tom','男','tom@163.com','18888888888')";//执行语句
    int i=statement.executeUpdate(sql);
    // 5、处理结果
    if (i > 0) {
        System.out.println("添加成功");
    }
    // 6、关闭连接
    statement.close();
    conn.close();
}
}

执行结果

2.改

编写修改数据库表中一条记录的测试类代码

代码

package test1;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
 
public class UpdateDemo {
 
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        Class.forName("com.mysql.cj.jdbc.Driver");
        Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbc?characterEncoding=utf8&useSSL=true", "root", "123456");
        Statement statement = conn.createStatement();
        statement.execute("INSERT INTO student VALUES(NULL,'zhangsan','男','zhangsan@163.com','16666666666')");
        int i=statement.executeUpdate("UPDATE student SET sname='rose',sex='女'  WHERE stuid=2");
        if(i>0) {
            System.out.println("修改成功！");
        }
        statement.close();
        conn.close();
    }
}

执行结果

3.查

编写查询数据库表中所有记录的测试类代码

代码

package test1;
 
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
 
import com.mysql.cj.xdevapi.Statement;
 
public class FindAllDemo {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
    Class.forName("com.mysql.cj.jdbc.Driver");
    Connection connection=DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbc?characterEncoding=utf8&useSSL=true", "root","123456");
    java.sql.Statement statement=connection.createStatement();
    ResultSet rs = statement.executeQuery("SELECT * FROM student");
    List<Student> stu = new ArrayList<Student>();
    while (rs.next()) {
        Student s = new Student();// 创建一个Student对象
        // 封装Student对象：把每个记录的字段值赋给Student对象的成员变量
        s.setStuld(rs.getInt("stuId"));
        s.setSname(rs.getString("sname"));
        s.setSex(rs.getString("sex"));
        s.setEmail(rs.getString("email"));
        s.setPhone(rs.getString("phone"));
        // 把封装的Student对象添加到stu集合
        stu.add(s);
    }
    stu.forEach(s -> System.out.println(s));
    rs.close();
    statement.close();
    connection.close();
}
}

执行结果

4.删

编写从数据库表删除一条记录的测试类代码

代码

package test1;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
 
public class DeleteDemo {
 
public static void main(String[] args) throws ClassNotFoundException, SQLException {
    Class.forName("com.mysql.cj.jdbc.Driver");
    Connection connection=DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbc?characterEncoding=utf8&useSSL=true", "root", "123456");
    Statement statement = connection.createStatement();
    int i= statement.executeUpdate("DELETE FROM student WHERE stuid=2");
    if(i>0) {
        System.out.println("删除成功");
    }
    statement.close();
    connection.close();
}
}

执行结果