Mybatis中处理特殊SQL处理逻辑解析

public interface SQLMapper {
    /**
     * 根据用户名模糊查询用户信息
     */
    List<User> getUserByLike(@Param("username") String username);
    /**
     * 批量删除
     */
    int deleteMore(String ids);
    /**
     * 查询指定表中的数据
     */
    List<User> getUserByTableName(String tableName);
    /**
     * 添加用户
     */
    void insetUser(User user);
}

public interface SQLMapper {
    /**
     * 根据用户名模糊查询用户信息
     */
    List<User> getUserByLike(@Param("username") String username);
}

<!--    List<User> getUserByLike(@Param("username") String username);-->
<!--    使用#{}，因为包括在单引号里，会被认为是字符串的一部分:select * from t_user where username like '%#{username}%'-->
<!--    三种方式-->
    <select id="getUserByLike" resultType="User">
     <!--  第一种 select * from t_user where username like '%${username}%'
       第二种 select * from t_user where username like concat('%', #{username}, '%')-->
       <!--第三种 推荐使用-->
        select * from t_user where username like "%"#{username}"%"
    </select>

<select id="selectLike" resultType="pojo.User">
	select * from user where user_name like '%#{username}%'
</select>

<select id="selectLike" resultType="pojo.User">
    select * from user where user_name like '%${username}%'
</select>

<select id="selectLike" resultType="pojo.User">
    select * from user where user_name like "%"#{username}"%"
</select>

<select id="selectLike" resultType="pojo.User">
    select * from user where user_name like concat('%',#{likeString},'%')
</select>

List<User> selectAllFromTable(@Param("tableName") String tableName);

<select id="selectAllFromTable" resultType="pojo.User">
    select * from #{tableName}
</select>

<select id="selectAllFromTable" resultType="pojo.User">
    select * from ${tableName}
</select>

<!--    void insetUser(User user);-->
<!--    方法的返回值是固定的
        useGeneratedKeys    设置当前标签中的sql使用了自增的主键 (id)
        keyProperty         将自增的主键的值 赋值给 传输到映射文件中的参数的某个属性（user.id）
-->
    <insert id="insetUser" useGeneratedKeys="true" keyProperty="id">
        insert into t_user values(null, #{username}, #{password},#{age},#{gender},#{email})
    </insert>

Integer deleteByIds(String Ids);

<delete id="deleteByIds">
    delete from user where id in (#{ids})
</delete>

<delete id="deleteByIds">
    delete from user where id in (${ids})
</delete>