JavaWeb-JDBC增删改查
目录1. MySQL准备
2. JDBC项目
3. JDBC新增
4. JDBC查询
5. JDBC修改
6. JDBC删除
内容
MySQL准备
[*]新建表t_person
CREATE TABLE `t_person` (
`id` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键',
`name` varchar(30) NOT NULL COMMENT '姓名',
`birthdate` datetime NOT NULL COMMENT '出生日期',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4;
JDBC项目
[*]创建项目
按照这篇博文搭建项目，博文地址
JDBC新增
注意新增步骤：
[*]加载驱动
[*]获取Connection
[*]创建Statement
[*]执行SQL语句(注意要写对)
[*]关闭资源
package com.example.aji;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
public static void main(String[] args) {
try {
//加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//mysql数据库相关信息
String url="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8";
String user="root";
String password="123456789";
//获取连接
Connection connection = DriverManager.getConnection(url,user,password);
Statement statement = connection.createStatement();
//新增语句
String insertSql="insert into t_person(name,birthdate) values('aji',now()),('aji',now())";
int result = statement.executeUpdate(insertSql);
//打印结果
System.out.println(result);
statement.close();
connection.close();
}catch (Exception e){
e.printStackTrace();
}
System.out.println("Hello world!");
}
}
JDBC查询
注意查询改骤：
[*]加载驱动
[*]获取Connection
[*]创建Statement
[*]执行SQL语句(注意修改条件要写对)
[*]解析ResultSet
[*]关闭资源
[*]ResultSet
[*]next()
while (resultSet.next())开始时游标在第一行
第一次遍历：
https://img2023.cnblogs.com/blog/3279853/202310/3279853-20231014195913617-1423154035.png
第二次遍历：
https://img2023.cnblogs.com/blog/3279853/202310/3279853-20231014200252254-263650015.png
第三次遍历：
https://img2023.cnblogs.com/blog/3279853/202310/3279853-20231014200324732-18337995.png
[*]getInt(String columnLabel)
从当前游标指向的行中获取字段名为columnLabel的字段的值，该值为int类型，该字段类型必须为INT
[*]getLong(String columnLabel)
从当前游标指向的行中获取字段名为columnLabel的字段的值，该值为long类型，该字段类型必须为BIGINT
[*]getString(String columnLabel)
从当前游标指向的行中获取字段名为columnLabel的字段的值，该值为String类型
[*]getDate(String columnLabel)
从当前游标指向的行中获取字段名为columnLabel的字段的值，该值为java.sql.Date类型
[*]更多
package com.example.aji;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
public static void main(String[] args) {
try {
//加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//mysql数据库相关信息
String url="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8";
String user="root";
String password="123456789";
//创建连接
Connection connection = DriverManager.getConnection(url,user,password);
Statement statement = connection.createStatement();
//查询语句
String querySql="select * from t_person";
ResultSet resultSet = statement.executeQuery(querySql);
while (resultSet.next()) {
System.out.print(resultSet.getInt("id"));
System.out.print(resultSet.getString("name"));
System.out.println(resultSet.getDate("birthdate"));
}
boolean execute = statement.execute(querySql);
System.out.println(execute);
resultSet.close();
statement.close();
connection.close();
}catch (Exception e){
e.printStackTrace();
}
System.out.println("Hello world!");
}
}
JDBC修改
注意新修改骤：
[*]加载驱动
[*]获取Connection
[*]创建Statement
[*]执行SQL语句(注意修改条件要写对)
[*]关闭资源
package com.example.aji;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
public static void main(String[] args) {
try {
//加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//mysql数据库相关信息
String url="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8";
String user="root";
String password="123456789";
//创建连接
Connection connection = DriverManager.getConnection(url,user,password);
Statement statement = connection.createStatement();
//修改语句
String updateSql="update t_person set name='xxxxx' where id=2";
int result = statement.executeUpdate(updateSql);
//打印结果
System.out.println(result);
//查询语句
String querySql="select * from t_person";
ResultSet resultSet = statement.executeQuery(querySql);
while (resultSet.next()) {
System.out.print(resultSet.getInt("id"));
System.out.print(resultSet.getString("name"));
System.out.println(resultSet.getDate("birthdate"));
}
boolean execute = statement.execute(querySql);
System.out.println(execute);
resultSet.close();
statement.close();
connection.close();
}catch (Exception e){
e.printStackTrace();
}
System.out.println("Hello world!");
}
}
JDBC删除
注意删除步骤：
[*]加载驱动
[*]获取Connection
[*]创建Statement
[*]执行SQL语句(注意删除条件要写对)
[*]关闭资源
package com.example.aji;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
public static void main(String[] args) {
try {
//加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//mysql数据库相关信息
String url="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8";
String user="root";
String password="123456789";
//创建连接
Connection connection = DriverManager.getConnection(url,user,password);
Statement statement = connection.createStatement();
//删除语句
String deleteSql="delete from t_person where id=2";
int result = statement.executeUpdate(deleteSql);
//打印结果
System.out.println(result);
//查询语句
String querySql="select * from t_person";
ResultSet resultSet = statement.executeQuery(querySql);
while (resultSet.next()) {
System.out.print(resultSet.getInt("id"));
System.out.print(resultSet.getString("name"));
System.out.println(resultSet.getDate("birthdate"));
}
boolean execute = statement.execute(querySql);
System.out.println(execute);
resultSet.close();
statement.close();
connection.close();
}catch (Exception e){
e.printStackTrace();
}
System.out.println("Hello world!");
}
}
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