Java 之连接 mysql 数据库 示例

Example to connect to the mysql database in java

For connecting java application with the mysql database, you need to follow 5 steps to perform database connectivity.



In this example we are using MySql as the database. So we need to know following informations for the mysql database:

Driver class: The driver class for the mysql database is com.mysql.jdbc.Driver.

Connection URL: The connection URL for the mysql database is jdbc:mysql://localhost:3306/sonoo where jdbc is the API, mysql is the database, localhost is the server name on which mysql is running, we may also use IP address, 3306 is the port number and sonoo is the database name. We may use any database, in such case, you need to replace the sonoo with your database name.

Username: The default username for the mysql database is root.

Password: Password is given by the user at the time of installing the mysql database. In this example, we are going to use root as the password.



1. Let's first create a table in the mysql database,  but before creating table, we need to create database first.

create database sonoo;  

use sonoo;  

create table emp(id int(10),name varchar(40),age int(3));  

2. Example to Connect Java Application with mysql database

In this example, sonoo is the database name, root is the username and password.

import java.sql.*;
class MysqlCon {
    public static void main(String args[]) {
        String url = "jdbc:mysql://localhost:3306/sonoo";
        String usr = "root";
        String pwd = "root";
        
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection connection = DriverManager.getConnection(url, usr, pwd);
            Statement stmt = connection.createStatement();
            ResultSet rs = stmt.executeQuery("select * from emp");
            while (rs.next()){
                System.out.println(rs.getInt(1) + "  " + rs.getString(2) + "  " + rs.getString(3));
            }
            connection.close();
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

3. To connect java application with the mysql database mysqlconnector.jar file is required to be loaded.

Two ways to load the jar file:

Way 1: Paste the mysqlconnector.jar file in JRE/lib/ext folder:

Download the mysqlconnector.jar file. Go to jre/lib/ext folder and paste the jar file here.


Way 2: 2) set classpath:

set the temporary classpath

C:>set classpath=c:\folder\mysql-connector-java-5.0.8-bin.jar;.;  

set the permanent classpath

Go to environment variable then click on new tab. In variable name write classpath and in variable value paste the path to the mysqlconnector.jar file by appending mysqlconnector.jar as

C:\folder\mysql-connector-java-5.0.8-bin.jar;.;

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Refer to:
https://www.javatpoint.com/example-to-connect-to-the-mysql-database





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