java 链接数据库增删改查
时间: 2023-08-19 22:03:55 浏览: 40
连接数据库增删改查是 Java 开发中常用的操作之一。以下是一个示例代码,用于连接 MySQL 数据库并进行增删改查操作:
```
import java.sql.*;
public class MySQLExample {
public static void main(String[] args) {
String url = "jdbc:mysql://localhost:3306/mydatabase";
String user = "root";
String password = "password";
try {
// 连接数据库
Connection conn = DriverManager.getConnection(url, user, password);
// 插入数据
String insertQuery = "INSERT INTO mytable (name, age) VALUES (?, ?)";
PreparedStatement pstmt = conn.prepareStatement(insertQuery);
pstmt.setString(1, "John");
pstmt.setInt(2, 25);
pstmt.executeUpdate();
// 查询数据
String selectQuery = "SELECT * FROM mytable";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(selectQuery);
while (rs.next()) {
System.out.println(rs.getString("name") + " " + rs.getInt("age"));
}
// 更新数据
String updateQuery = "UPDATE mytable SET age = ? WHERE name = ?";
PreparedStatement pstmt2 = conn.prepareStatement(updateQuery);
pstmt2.setInt(1, 30);
pstmt2.setString(2, "John");
pstmt2.executeUpdate();
// 删除数据
String deleteQuery = "DELETE FROM mytable WHERE name = ?";
PreparedStatement pstmt3 = conn.prepareStatement(deleteQuery);
pstmt3.setString(1, "John");
pstmt3.executeUpdate();
// 关闭连接
rs.close();
pstmt.close();
pstmt2.close();
pstmt3.close();
stmt.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
```
需要注意的是,上述代码中的 `url`、`user` 和 `password` 分别代表数据库的 URL、用户名和密码,需要根据实际情况进行修改。同时,操作数据库时需要使用 `PreparedStatement` 或 `Statement` 来执行 SQL 语句,避免 SQL 注入攻击。