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java如何增删改查

2026-03-18 22:37:23Java

增删改查操作示例

在Java中，增删改查（CRUD）操作通常涉及数据库交互，以下以JDBC和MyBatis为例说明实现方式。

JDBC实现

数据库连接配置

String url = "jdbc:mysql://localhost:3306/test";
String user = "root";
String password = "123456";
Connection conn = DriverManager.getConnection(url, user, password);

增加数据（Create）

String sql = "INSERT INTO users(name, age) VALUES(?, ?)";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, "张三");
pstmt.setInt(2, 25);
pstmt.executeUpdate();

删除数据（Delete）

String sql = "DELETE FROM users WHERE id = ?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, 1);
pstmt.executeUpdate();

修改数据（Update）

java如何增删改查

String sql = "UPDATE users SET name = ? WHERE id = ?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, "李四");
pstmt.setInt(2, 2);
pstmt.executeUpdate();

查询数据（Read）

String sql = "SELECT * FROM users";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql);
while (rs.next()) {
    System.out.println(rs.getInt("id") + " " + rs.getString("name"));
}

MyBatis实现

Mapper接口定义

public interface UserMapper {
    void insert(User user);
    void deleteById(int id);
    void update(User user);
    User selectById(int id);
}

XML映射文件

java如何增删改查

<!-- 插入 -->
<insert id="insert" parameterType="User">
    INSERT INTO users(name, age) VALUES(#{name}, #{age})
</insert>

<!-- 删除 -->
<delete id="deleteById">
    DELETE FROM users WHERE id = #{id}
</delete>

<!-- 更新 -->
<update id="update" parameterType="User">
    UPDATE users SET name=#{name} WHERE id=#{id}
</update>

<!-- 查询 -->
<select id="selectById" resultType="User">
    SELECT * FROM users WHERE id = #{id}
</select>

Spring Data JPA实现

实体类定义

@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue
    private Integer id;
    private String name;
    private Integer age;
    // getters/setters
}

Repository接口

public interface UserRepository extends JpaRepository<User, Integer> {
}

服务层调用

// 保存
userRepository.save(new User("王五", 30));

// 删除
userRepository.deleteById(1);

// 更新
User user = userRepository.findById(2).get();
user.setName("赵六");
userRepository.save(user);

// 查询
List<User> users = userRepository.findAll();