java简单jdbc查询操作

- 日理万妓 2022-06-08 01:29 204阅读 0赞

所采用的mysql的数据库驱动版本：5.0.8

mysql-connector-java-5.0.8-bin.jar

程序结构图：

> ![Center][]

表结构：

![Center 1][]

创表sql:

<table> 
 <tbody> 
  <tr> 
   <td>Create Table</td> 
  </tr> 
  <tr> 
   <td><br> CREATE&nbsp;TABLE&nbsp;`users`&nbsp;(<br> &nbsp;&nbsp;`id`&nbsp;int(11)&nbsp;NOT&nbsp;NULL&nbsp;AUTO_INCREMENT,<br> &nbsp;&nbsp;`username`&nbsp;varchar(200)&nbsp;DEFAULT&nbsp;NULL,<br> &nbsp;&nbsp;`password`&nbsp;varchar(32)&nbsp;DEFAULT&nbsp;NULL,<br> &nbsp;&nbsp;`sex`&nbsp;char(1)&nbsp;DEFAULT&nbsp;NULL,<br> &nbsp;&nbsp;`birthday`&nbsp;date&nbsp;DEFAULT&nbsp;NULL,<br> &nbsp;&nbsp;PRIMARY&nbsp;KEY&nbsp;(`id`)<br> )&nbsp;ENGINE=InnoDB&nbsp;AUTO_INCREMENT=17&nbsp;DEFAULT&nbsp;CHARSET=utf8</td> 
  </tr> 
 </tbody> 
</table>

package com.itheima.mydatis.jdbc;  
  
  
import java.sql.Connection;  
import java.sql.DriverManager;  
import java.sql.PreparedStatement;  
import java.sql.ResultSet;  
import java.sql.SQLException;  
import java.util.Date;  
  
  
  
  
public class JdbcTest \{  
  
// 定义sql  
private static String sql = "SELECT \* FROM users t WHERE t.username LIKE ?";  
  
public static void main(String\[\] args) throws SQLException \{  
// 连接对象  
Connection connection = null;  
// 预编译对象 PreparedStatement  
PreparedStatement preparedStatement = null;  
// 结果集  
ResultSet resultSet = null;  
  
  
try \{  
// 加载驱动  
Class.forName("com.mysql.jdbc.Driver");  
// 获取连接对象  
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mybatisdb", "root", "123");  
// 获取preparedStatement  
preparedStatement = connection.prepareStatement(sql);  
// 为preparedStatement对象的sql中的占位符设置参数  
preparedStatement.setString(1, "%张%");  
// 执行sql语句，并返回结果集到resultSet中  
resultSet = preparedStatement.executeQuery();  
// 遍历结果集  
while (resultSet.next()) \{  
int id = resultSet.getInt("id");  
String username = resultSet.getString("username");  
Date birthday = resultSet.getDate("birthday");  
System.out.println(id + "--" + username + "--" + birthday);  
\}  
  
\} catch (Exception e) \{  
e.printStackTrace();  
\} finally \{  
// 释放资源  
if (resultSet != null) \{  
resultSet.close();  
\}  
if (preparedStatement != null) \{  
preparedStatement.close();  
\}  
if (connection != null) \{  
connection.close();  
\}  
\}  
\}  
\}

执行结果：

![Center 2][]

[Center]: /images/20220608/a57e39de912d4a1a9cadc0e495dc2ccc.png
[Center 1]: /images/20220608/c1a486f737304cbd9100fed8ce95a648.png
[Center 2]: /images/20220608/15eee6eb667e470ea2b38599436fd225.png