[JAVA] JDBC database access basic steps

import java.sql.*;

public class JDBC {
	
	public static void main(String []args) throws ClassNotFoundException, SQLException {
	
		//加载驱动
			Class.forName("com.mysql.jdbc.Driver");
		//建立连接对象
			Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test","root","root");
		//创建语句对象
			Statement st =conn.createStatement();
			String sql="select * from user";
		//执行语句获得查询结果
			ResultSet rs=st.executeQuery(sql);
			System.out.println("uid\tname\tpassword\t");
			while(rs.next()) {//rs是所有行构成的结合，对集合循环遍历，.next()判断下一行有没有东西
				System.out.print(rs.getString(1)+"\t");//获取第一列
				System.out.print(rs.getString(2)+"\t");//获取第二列	
				System.out.print(rs.getString(3)+"\n");//获取第三列
			}	
	}
}

Result of the program:

Corresponding to the database:

 Enhanced Edition:

import java.sql.*;
import java.util.Scanner;

public class JDBC {
	
	public static void main(String []args) throws ClassNotFoundException, SQLException {
	
		//1.加载驱动
			Class.forName("com.mysql.jdbc.Driver");
		//2.建立连接对象
			Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test","root","root");
		//3.创建语句对象
			Statement st =conn.createStatement();
			String sql="select * from user";
			String sql2 = "insert into user values('5','dog','123456')";
		//4.执行语句获得查询结果
			//①查询语句用st.executeAuery(sql)
			ResultSet rs=st.executeQuery(sql);
			System.out.println("uid\tname\tpassword\t");
			while(rs.next()) {//rs是所有行构成的结合，对集合循环遍历，.next()判断下一行有没有东西
				System.out.print(rs.getString(1)+"\t");//获取第一列
				System.out.print(rs.getString(2)+"\t");//获取第二列	
				System.out.print(rs.getString(3)+"\n");//获取第三列
			}
			Statement st2 =conn.createStatement();
			//DML语言用st.executeUpdate(sql),返回影响的函数
			int i=st2.executeUpdate(sql2);
			System.out.println(i);		
			
			
			//练习一下怎么输入
			//Scanner s=new Scanner(System.in);
			//int intt=s.nextInt();
			
			
			//从新查一下
			ResultSet rs2=st.executeQuery(sql);
			System.out.println("uid\tname\tpassword\t");
			while(rs2.next()) {//rs是所有行构成的结合，对集合循环遍历，.next()判断下一行有没有东西
				System.out.print(rs2.getString(1)+"\t");//获取第一列
				System.out.print(rs2.getString(2)+"\t");//获取第二列	
				System.out.print(rs2.getString(3)+"\n");//获取第三列
			}
			
			//或者可以使用预编译
			String sql3="select * from user where uid=? and name=?;";//可以使用占位符
			PreparedStatement p=conn.prepareStatement(sql3);//这里就可以先传进去
			p.setString(1,"1");
			p.setString(2,"Admin");
			ResultSet rs3=p.executeQuery();//这里就不用再传了
			System.out.println("uid\tname\tpassword\t");
			while(rs3.next()) {//rs是所有行构成的结合，对集合循环遍历，.next()判断下一行有没有东西
				System.out.print(rs3.getString(1)+"\t");//获取第一列
				System.out.print(rs3.getString(2)+"\t");//获取第二列	
				System.out.print(rs3.getString(3)+"\n");//获取第三列
			}
			
		
	}
}

operation result:

 database: