查询几所学校特定时间的相关数据

今天自己写的一条SQL语句，用到了表连接和临时表，语法供自己以后参考。

SELECT

    us.school_name 学校名称,

    CONCAT(

        ug.grade_name,

        uc.classes_name

    ) 年级班级,

    uu.user_id 用户ID,

    uu.user_real_name 学生姓名,

    ta.assignment_id 作业序号,

    ta.assignment_write_time 作文写作耗时（以秒记）,

    ta.assignment_word_count 字数,

    ta.assignment_submit_count 作文提交次数,

    ta.assignment_start_date 布置作业开始时间,

    ta.assignment_end_date 作业截止时间,

    ta.assignment_submit_date 作业提交教师时间,

    ta.assignment_mark1 作业评分的第一项（内容）,

    ta.assignment_mark2 作业评分的第二项（语言）,

    ta.assignment_mark3 作业评分的第三项（文采或结构）,

    ta.assignment_mark_sum 三项评分的总分,

    teacher_list.user_real_name 教师姓名

FROM

    t_assignment ta

LEFT JOIN u_user uu ON ta.user_id = uu.user_id

LEFT JOIN u_classes_user ucu ON uu.user_id = ucu.user_id

LEFT JOIN u_classes uc ON ucu.classes_id = uc.classes_id

LEFT JOIN u_school_grade usg ON uc.school_grade_id = usg.school_grade_id

LEFT JOIN u_grade ug ON usg.grade_id = ug.grade_id

LEFT JOIN u_school us ON usg.school_id = us.school_id

LEFT JOIN u_user_role uur ON uu.user_id = uur.user_id

LEFT JOIN u_role ur ON uur.role_id = ur.role_id

LEFT JOIN (

    SELECT

        ucu.classes_id,

        uu.user_real_name

    FROM

        u_user uu

    LEFT JOIN u_user_role uur ON uu.user_id = uur.user_id

    LEFT JOIN u_role ur ON uur.role_id = ur.role_id

    LEFT JOIN u_classes_user ucu ON uu.user_id = ucu.user_id

    WHERE

        uur.role_id = '42'

) teacher_list ON teacher_list.classes_id = ucu.classes_id

WHERE

    ta.assignment_start_date > '2014-09-01 00:00:00'

AND ta.assignment_start_date < '2015-01-31'

AND uur.role_id = '38'

AND us.school_id IN ('7', '8', '5', '2');