详解MyBatis增删改查SQL案例实战

public class User {
    private Integer id;
    private String username;
    private String password;
    private String email;

    // Getter和Setter方法
}

int insertUser(User user);

<insert id="insertUser" parameterType="User">
    INSERT INTO user (username, password, email)
    VALUES (#{username}, #{password}, #{email})
</insert>

User user = new User();
user.setUsername("testUser");
user.setPassword("123456");
user.setEmail("test@example.com");

int result = userMapper.insertUser(user);
System.out.println("插入结果：" + result); // 影响的行数

User getUserById(Integer id);

<select id="getUserById" parameterType="int" resultType="User">
    SELECT * FROM user WHERE id = #{id}
</select>

User user = userMapper.getUserById(1);
System.out.println("查询结果：" + user.getUsername());

int updateUser(User user);

<update id="updateUser" parameterType="User">
    UPDATE user
    SET username = #{username},
        password = #{password},
        email = #{email}
    WHERE id = #{id}
</update>

User user = new User();
user.setId(1);
user.setUsername("updatedUser");
user.setPassword("newPassword");
user.setEmail("updated@example.com");

int result = userMapper.updateUser(user);
System.out.println("更新结果：" + result); // 影响的行数

int deleteUserById(Integer id);

<delete id="deleteUserById" parameterType="int">
    DELETE FROM user WHERE id = #{id}
</delete>

int result = userMapper.deleteUserById(1);
System.out.println("删除结果：" + result); // 影响的行数

List<User> searchUsers(@Param("keyword") String keyword);

<select id="searchUsers" resultType="User">
    SELECT * FROM user
    WHERE username LIKE CONCAT('%', #{keyword}, '%')
</select>

List<User> users = userMapper.searchUsers("test");
users.forEach(user -> System.out.println(user.getUsername()));

int insertBatch(List<User> users);

<insert id="insertBatch" parameterType="list">
    INSERT INTO user (username, password, email)
    VALUES
    <foreach collection="list" item="user" separator=",">
        (#{user.username}, #{user.password}, #{user.email})
    </foreach>
</insert>

List<User> users = new ArrayList<>();
users.add(new User("user1", "123", "user1@example.com"));
users.add(new User("user2", "456", "user2@example.com"));

int result = userMapper.insertBatch(users);
System.out.println("批量插入结果：" + result);