MySQL small practice (using JDBC to operate the database)

topic:

1. Create a database (student number + name abbreviation, such as: 2020001zs) and create a table (more than five fields) in the database;

2. Use JDBC (using the PreparedStatement interface) to operate the database to add, delete, modify and query the data in the table

Table of contents

1. Database

1. Prepare the environment

2. Query data

3. Add data

4. Delete data

5. Modify data

1. Database

1. Create a database

2. Create a table

The title says: Create a table (more than five fields) in the database, let’s get 5

drop table if exists student_course;
create table student_course
(
    course_id     varchar(10)  comment '课程号',
    course_name   varchar(15) comment '课程名',
    course_number double unsigned comment '学分数',
    student_time  int unsigned comment '学时数',
    teacher       varchar(10) comment '任课教师'
)
    comment '课程表';

select *
from student_course;

3. Add data


INSERT INTO student_course
values ('K001', '计算机图形学', 2.5, 40, '胡晶晶'),
       ('K002', '计算机应用基础', 3, 48, '任泉'),
       ('K006', '数据结构', 4, 64, '马跃先'),
       ('M001', '政治经济学', 4, 64, '孔繁新'),
       ('S001', '高等数学', 3, 48, '赵晓尘');

			 select *
from student_course;

2. JDBC

1. Prepare the environment

Click to enter the mysql jar package download official website

If MySQL is version 5:

My mysql is version 8, so download this:

Unzip:

2. Query data

The driver file jar package of version 5.x corresponds to:
Class.forName("com.mysql.jdbc.Driver");
statement to load the database driver

And I am using the 8.0x version of the database driver file. For this, the statement of loading the database driver needs to be changed to:
Class.forName("com.mysql.cj.jdbc.Driver");

import java.sql.*;

public class Main {

    public static void main(String[] args) throws Exception {
        PreparedStatement ps = null;
        Connection con = null;
        ResultSet rs = null;

        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/20202122084tsj?serverTimezone=GMT%2B8", "root", "root");
            String sql = "select * from student_course;";
            ps = con.prepareStatement(sql);
            rs = ps.executeQuery();
            while (rs.next()) {
                System.out.println("编号:" + rs.getString(1) + "\t" + "课程名:" + rs.getString(2) + "\t" + "学分数:" + rs.getString(3) + "\t" + "学时数:" + rs.getString(4) + "\t" + "任课教师:" + rs.getString(5));
            }

            rs.close();
            ps.close();
            con.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


}

3. Add data

import java.sql.*;
public class InsertData {
    public static void main(String[] args) {
        Connection con = null;
        PreparedStatement ps = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/20202122084tsj?serverTimezone=GMT%2B8", "root", "root");
            String sql = "INSERT INTO student_course values(?,?,?,?,?);";
            ps = con.prepareStatement(sql);
            ps.setString(1, "K111");
            ps.setString(2, "javaWeb");
            ps.setDouble(3, 3);
            ps.setInt(4, 48);
            ps.setString(5, "丁老师");
            ps.execute();
            ps.close();
            con.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

4. Delete data

import java.sql.*;

public class DeleteData {
    public static void main(String[] args){
        Connection con = null;
        PreparedStatement ps = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/20202122084tsj?serverTimezone=GMT%2B8", "root", "root");
            String sql = "delete from student_course where course_id  = ?;";
            ps = con.prepareStatement(sql);
            ps.setString(1,"K111");
            ps.execute();
            ps.close();
            con.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

Previously added data is removed

5. Modify data

import java.sql.*;

public class UpdateData {
    public static void main(String[] ags){
        Connection con = null;
        PreparedStatement ps = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/20202122084tsj?serverTimezone=GMT%2B8", "root", "root");
            String sql = "update student_course set course_name = ?,teacher = ? where course_id  = ?;";
            ps = con.prepareStatement(sql);
            ps.setString(1,"SpringCloud");
            ps.setString(2,"王老师");
            ps.setString(3,"S001");
            ps.execute();
            ps.close();
            con.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

The code redundancy is serious, and there will be tool class simplification in the future