Java How to connect MySQL database and perform basic SQL statements --JDBC basic operations

Connect to the database

1, into the jar package mysql-connector-java-5.1.12- bin.jar, the version number may be selected according to the MySQL version

2, the registration drive: Class.forName("com.mysql.cj.jdbc.Driver");
3, MySQL connection link provided: String url ="jdbc:mysql://192.168.91.4:3306/myDB" \\myDB为一个数据库的库名;
4 ,; created connecting channel and MySQL:Connection conn=DriverManager.getConnection(url, "root", "123456")； \\root 为用户名 ，123456为密码

Database operations

1, defines an executor to execute the SQL statement: Statement stat= conn.createStatement();
2, corresponding to execute SQL statements

	String sql1=
				"create table if not exists user(account varchar(20) PRIMARY key,password varchar(20))";
		String sql2 ="insert into user values('ZepngLin','12345')";			
		stat.execute(sql1);
		stat.execute(sql2);
		

Query the database

Use ResultSet class receives the query result, the class is equivalent to a two-dimensional array

		String sql4 ="select * from user";
		ResultSet re= stat.executeQuery(sql4);

Traverse the result set:

			while(re.next()) {
				System.out.println(re.getString(1)+" "+re.getString(2));  //按序号查找，序号从1开始，也可以按字段名查找
			}
			

After the close of each object conserve resources

			conn.close();
			stat.close();
			re.close();

With code (content clutter is merely test code)

package myTestProject;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import com.mysql.cj.jdbc.Driver;
import com.mysql.cj.protocol.Resultset;
public class DB {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String url ="jdbc:mysql://192.168.91.4:3306/myDB";
		String sql1=
				"create table if not exists user(account varchar(20) PRIMARY key,password varchar(20))";
		String sql2 ="insert into user values('ZepngLin','12345')";
		String sql3 ="insert into user values('Wefngdai','54321')";
		String sql4 ="select * from user";
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			System.out.println("注册驱动成功");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			System.out.println("注册驱动失败");
			e.printStackTrace();
			return ;
		}
		Connection conn=null;
		try {
			conn=DriverManager.getConnection(url, "root", "ZepngLin_42");
			Statement  stat= conn.createStatement();
			stat.execute(sql1);
			stat.execute(sql2);
			stat.execute(sql3);
			ResultSet re= stat.executeQuery(sql4);
			while(re.next()) {
				System.out.println(re.getString(1)+" "+re.getString(2));
			}
			conn.close();
			stat.close();
			re.close();
			System.out.println("连接数据库成功");
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			System.out.println("连接数据库失败");
			e.printStackTrace();
			return;
		}
		
		
	}

}