14 JDBC

什么是JDBC : Java连接数据库!

JDBC示意图

需要jar包的支持:

java.sql
javax.sql
mysql-conneter-java.... 连接驱动（(必须要导入)

导入数据库依赖

<! --mysq1的驱动-->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysq1-connector-java</artifactId>
    <version>5.1.47</version>
</dependency>

CREATE TABLE users(
    id lNT PRIMARY KEY,
    `name` VARCHAR(40),
    `password` VARCHAR(40),
    email VARCHAR(60),
    birthday DATE
);
INSERT INTO users(id, `name`, `password` ,email, birthday)
VALUES(1,'张三','123456','zs@qq.com', '2000-01-01');
INSERT INTO users(id, `name`, `password` ,email, birthday)
VALUES(2,'李四';'123456', 'Is@qq.com'; '2000-01-01');
NSERT INTO users(id, `name`, `password`, email, birthday)
VALUES(3,'王五','123456','ww@qq.com' ; '2000-01-01'");

package com.karl.test;
import java.sql.*;
public class TestJdbc {
    public static void main(String[] args) throws ClassNotFoundException，sQLException {
    //配置信息
    //useUnicode=true&characterEncoding=utf-8解决中文乱码
    String url="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8";
    String username = "root";
    String password = "123456";
    //1.加载驱动
    Class.forName("com.mysql.jdbc.Driver" );
    //2.连接数据库，代表数据库
    Connection connection = DriverManager.getConnection(url，username，password);
    //3.向数据库发送SQL的对象Statement : CRUD
    Statement statement = connection.createstatement();
    //4.编写SQL
    string sql = "select * from users";
    //5.执行查询SQL，返回一个Resultset :结果集
    Resultset rs = statement.executeQuery(sql);
    while (rs.next()){
        system.out.println("id="+rs.getobject("id"));
        system.out.println("name="+rs.getobject("name"));
        system.out.println("password="+rs.getobject("password"));
        system.out.println("email="+rs.getobject("email"));
        system.out.println("birthday="+rs.getobject("birthday"));
    }
    //6.关闭连接，释放资源（一定要做)先开后关
    rs.close();
    statement.close();
    connection.close();

IDEA中连接数据库

JDBC固定步骤:

加载驱动
连接数据库,代表数据库
向数据库发送SQL的对象Statement : CRUD
编写sQL(根据业务，不同的SQL)
执行SQL
关闭连接

预编译

//1.加载驱动
class.forName( "com.mysq1.jdbc.Driver" ) ;
//2.连接数据库,代表数据库
Connection connection = DriverManager.getConnection(url，username，password);
//3.编写SQL
string sql = "insert into users(id，name，password，email， birthday) values (?,?,?,?,?);";
//4.预编译
PreparedStatement preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt( parameterIndex: 1, x: 4);//给第一个占位符?的值赋值为1;
preparedStatement.setString( parameterlndex: 2，x:"狂神说Java");//给第二个占位符?的值赋值为狂神说Java;
preparedStatement.setString( parameterlndex: 3, x:"123456");//给第三个占位符?的值赋值为123456;
preparedStatement . setString( parameterlndex: 4, x:"24736743@qq.com");//给第四个占位符?的值赋值;
preparedStatement.setDate( parameterlndex: 5,new Date(new java.util.Date().getTime()));
//5.执行SQL
int i = preparedstatement.executeUpdate();
if (i>0){
    system.out.print1n("插入成功@");
}
//6.关闭连接，释放资源（一定要做)先开后关
preparedStatement.close();
connection.close();