Record the first JDBC

JDBC What are the

bring Java Connect to database ; Can pass java Drive different databases uniformly .

To configure JDBC

Guide pack

$1.$ MySQL I use it 5.7.19, then maven Failed to import package , There is no corresponding one on the official website jar package , Finally, I saw a post saying ,5.7 Version of MySQL Direct use mysql-connector-java-5.1.34.jar The above jar Just a bag ;
$2.$ Then import jar After package , Connect MySQL You need to set the time zone , Set to GMT Just ok 了 ;

$3.$ After entering the user's password Click on test connection

$4.$ Click on Schemas

I was then Schemas It's always empty , I found a lot of information and didn't solve it , The last restart idea Just fine ;
$5.$ After successful connection , The database information can be displayed .

Insert a row

package com.tl.study01;

import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

/** * @author tl *  Insert a row  id value （ key ） Can't repeat  */
public class TestJdbc02 {
    
    public static void main(String[] args) throws Exception {
    
        // Configuration information 
        //useUnicode=true&characterEncoding=utf-8  Solve the Chinese garbled code 
        String url="jdbc:mysql://localhost:3306/jdbc_study?" +
                "useUnicode=true&characterEncoding=utf-8";
        String username = "root";
        String password = "123";

        //1. The load driver 
        Class.forName("com.mysql.jdbc.Driver");
        //2. Connect to database ,connection On behalf of the database 
        Connection connection = DriverManager.getConnection(url, username, password);
        //3. To write SQL
        String sql = "insert into users(id, name, password, email, birthday) values (?,?,?,?,?);";
        //4. precompile （ Security ）
        PreparedStatement preparedStatement = connection.prepareStatement(sql);
        // Give the first placeholder ？  The value of is assigned to 4;
        preparedStatement.setInt(1,4);
        // Give the second placeholder ？  The value of is assigned to root;
        preparedStatement.setString(2,"root");
        // Give the third placeholder ？  The value of is assigned to 123;
        preparedStatement.setString(3,"123");
        // Give the fourth placeholder ？  The value of is assigned to [email protected];
        preparedStatement.setString(4,"[email protected]");
        // Give the fifth placeholder ？  The value of is assigned to new Date(new java.util.Date().getTime());
        preparedStatement.setDate(5,new Date(new java.util.Date().getTime()));

        //5. perform SQL
        int i = preparedStatement.executeUpdate();

        if (i>0){
    
            System.out.println(" Insert the success @");
        }

        //6. Close the connection , Release resources （ Be sure to do ）  Turn it on and off 
        preparedStatement.close();
        connection.close();
    }
}

Delete a line

package com.tl.study01;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

/** * @author tl *  Delete a line  */
public class TestJdbc03 {
    
    public static void main(String[] args) throws Exception {
    
        // Configuration information 
        //useUnicode=true&characterEncoding=utf-8  Solve the Chinese garbled code 
        String url="jdbc:mysql://localhost:3306/jdbc_study?" +
                "useUnicode=true&characterEncoding=utf-8";
        String username = "root";
        String password = "123";
        //1. The load driver 
        Class.forName("com.mysql.jdbc.Driver");
        //2. Connect to database ,connection On behalf of the database 
        Connection connection = DriverManager.getConnection(url, username, password);
        //3. To write SQL
        String sql = "delete from users where id =2";
        //4. precompile （ Security ）
        PreparedStatement preparedStatement = connection.prepareStatement(sql);
        int i = preparedStatement.executeUpdate(sql);
        if (i>0){
    
            System.out.println(" Delete successful @");
        }
        //6. Close the connection , Release resources （ Be sure to do ）  Turn it on and off 
        preparedStatement.close();
        connection.close();
    }
}

Query table information

package com.tl.study01;

import java.sql.*;

/** * @author tl *  Look up the table  */
public class TestJdbc01 {
    
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
    
        //"useUnicode=true&characterEncoding=utf-8" Solve the Chinese garbled code 
        String url="jdbc:mysql://localhost:3306/jdbc_study?" +
                "useUnicode=true&characterEncoding=utf-8";
        String username = "root";
        String password ="123";
        // Drive by reflection loading 
        Class.forName("com.mysql.jdbc.Driver");
        // Connect to database ,connection On behalf of the database 
        Connection connection = DriverManager.getConnection(url, username, password);
        // Send to the database SQL The object of Statement:CRUD
        Statement statement = connection.createStatement();// unsafe 
        // To write SQL  Execute the query SQL, Return to one ResultSet: Result set 
        String sql ="select * from users";
        ResultSet res = statement.executeQuery(sql);

        while (res.next()){
    
            System.out.println("id="+res.getObject("id"));
            System.out.println("name="+res.getObject("name"));
            System.out.println("password="+res.getObject("password"));
            System.out.println("email="+res.getObject("email"));
            System.out.println("birthday="+res.getObject("birthday"));
        }
        //6. Close the connection , Release resources （ Be sure to do ）  Turn it on and off 
        res.close();
        statement.close();
        connection.close();
    }
}