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SQLstatement=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SQLResultSet 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SQLstatement=connection.createStatement();String sql="Select * From product ";//4.执行SQLResultSet 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SQLString 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SQLstatement.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SQLString 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SQLstatement.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SQLString 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SQLstatement.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SQLString 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SQLstatement.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。
