使用JDBC操作数据库
使用JDBC查询数据
五部曲：建立驱动，建立连接，获取SQL语句，执行SQL语句，释放资源
建立驱动
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");建立连接
//2.连接数据库
String url="jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC";
String username="root";
String password="123456";
connection=DriverManager.getConnection(url,username,password);获取SQL语句
//3。获取SQL
statement=connection.createStatement();
String sql="Select * From product ";执行SQL语句
这里用了个ResultSet来接收查询到的数据，见名知意，ResultSet--结果集
//4.执行SQL
ResultSet resultSet=statement.executeQuery(sql);
while (resultSet.next()){
Long ID=resultSet.getLong("id");
String productName=resultSet.getString("productName");
Double salePrice=resultSet.getDouble("salePrice");
System.out.println(ID);
System.out.println(productName);
System.out.println(salePrice);
}释放资源
statement.close();
connection.close();运行结果（因结果篇幅过大，故此处只展示部分结构）：
完整参考代码：
public class JDBC2 {
public static void main(String[] args) throws Exception {
Connection connection=null;//初始化
Statement statement=null;//初始化
try{
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.连接数据库
String url="jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC";
String username="root";
String password="123456";
connection=DriverManager.getConnection(url,username,password);
//3。获取SQL
statement=connection.createStatement();
String sql="Select * From product ";
//4.执行SQL
ResultSet resultSet=statement.executeQuery(sql);
while (resultSet.next()){
Long ID=resultSet.getLong("id");
String productName=resultSet.getString("productName");
Double salePrice=resultSet.getDouble("salePrice");
System.out.println(ID);
System.out.println(productName);
System.out.println(salePrice);
}
//5.释放资源
try {
statement.close();
}catch (SQLException e){
e.printStackTrace();
}
try {
connection.close();
}catch (SQLException e){
e.printStackTrace();
}
}catch (Exception e){
e.printStackTrace();
}
}
}
使用JDBC修改数据
五步曲再来一遍
建立驱动
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");建立连接
//2.建立连接
String url="jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC";
String username="root";
String password="123456";
connection= DriverManager.getConnection(url,username,password);获取SQL语句
//3.获取SQL
String sql="UPDATE `test`.`product` SET `productName` = '罗技M90', `dir_id` = 3, `salePrice` = 90.00, `supplier` = '罗技', `brand` = '罗技', `cutoff` = 0.50, `costPrice` = 35.00 WHERE `id` = 22;\n";
statement=connection.createStatement();执行SQL语句
//4.执行SQL
statement.executeUpdate(sql);
System.out.println("更新数据成功");释放资源
//释放资源
statement.close();
connection.close();
运行结果:
完整代码参考
package com.WEB.JDBC;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class JDBC4 {
public static void main(String[] args) throws Exception {
Connection connection=null;
Statement statement=null;
try {
//1.注册驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.连接数据库
String url="jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC";
String username="root";
String password="020315";
connection= DriverManager.getConnection(url,username,password);
//3.获取SQL
String sql="UPDATE `test`.`product` SET `productName` = '罗技M90', `dir_id` = 3, `salePrice` = 90.00, `supplier` = '罗技', `brand` = '罗技', `cutoff` = 0.50, `costPrice` = 35.00 WHERE `id` = 22;\n";
statement=connection.createStatement();
//4.执行SQL
statement.executeUpdate(sql);
System.out.println("更新数据成功");
//5.释放资源
try {
statement.close();
}catch (SQLException e){
e.printStackTrace();
}
try {
connection.close();
}catch (SQLException e){
e.printStackTrace();
}
}catch (Exception e){
e.printStackTrace();
}
}
}
使用JDBC插入数据
五步曲再再来一遍
建立驱动
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");建立连接
//2.建立连接
String url="jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC";
String username="root";
String password="123456";
connection= DriverManager.getConnection(url,username,password);获取SQL语句
//3.获取SQL
String sql="INSERT INTO `test`.`product`(`id`, `productName`, `dir_id`, `salePrice`, `supplier`, `brand`, `cutoff`, `costPrice`) VALUES (null, 'ROG极恶之眼', 3, 1190.00, 'ROG', 'ROG', 0.50, 1135.00);\n";
statement=connection.createStatement();执行SQL语句
//4.执行SQL
statement.executeUpdate(sql);
System.out.println("插入数据成功");释放资源
//释放资源
statement.close();
connection.close();
运行结果:
完整代码参考：
public class JDBC3 {
public static void main(String[] args) throws Exception {
try {
Connection connection=null;
Statement statement=null;
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.建立连接
String url="jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC";
String username="root";
String password="123456";
connection= DriverManager.getConnection(url,username,password);
//3.获取SQL
String sql="INSERT INTO `test`.`product`(`id`, `productName`, `dir_id`, `salePrice`, `supplier`, `brand`, `cutoff`, `costPrice`) VALUES (null, 'ROG极恶之眼', 3, 1190.00, 'ROG', 'ROG', 0.50, 1135.00);\n";
statement=connection.createStatement();
//4.执行SQL
statement.executeUpdate(sql);
System.out.println("插入数据成功");
//5.释放资源
try {
statement.close();
}catch (SQLException e){
e.printStackTrace();
}
try {
connection.close();
}catch (SQLException e){
e.printStackTrace();
}
}catch (Exception e){
e.printStackTrace();
}
}
}
写在最后：JDBC是JAVA操作数据的规范，我的面试官曾经和我说过一句话："要是能够把JDBC那些语句默写出来，那么Mybatis肯定是没有问题。"JDBC是规范，也是Mybatis基于封装的东西，基础语句要多加练习，这样才能熟能生巧。笔者小，中，大厂均有面试经历，每日分享JAVA全栈知识，希望与大家共同进步。
