寫(xiě)作業(yè)的思考。假如有這么一個(gè)簽到系統(tǒng)

按照范式設(shè)計(jì)有

學(xué)院表
課表(學(xué)院課表一對(duì)多)
老師表
學(xué)生表
教課表(老師課表多對(duì)多)
上課表(學(xué)生課表多對(duì)多)
排課表(課表排課一對(duì)多)
簽到表(排課簽到一對(duì)多)
簽到記錄表(簽到，簽到記錄一對(duì)多)

假如設(shè)定兩個(gè)查詢
學(xué)生由學(xué)號(hào)和課號(hào)查詢簽到
教師由教工號(hào)和課號(hào)查詢

而在我實(shí)現(xiàn)這個(gè)系統(tǒng)時(shí)，隨便一個(gè)查詢動(dòng)作都建立了好多張表，為了獲取排課，課程，老師，學(xué)院信息。

我覺(jué)得這樣做，，有點(diǎn)麻煩？可是把它放到代碼實(shí)現(xiàn)也要不斷發(fā)起查詢很多次呀。。

比如這是我剛剛寫(xiě)的，，一個(gè)獲取這個(gè)學(xué)生本周需要簽到的課程，我想看看瞎幾把寫(xiě)可以聯(lián)立成什么樣子，。功能的目的我達(dá)到了

        SELECT
        att.user_usr_id, att.course_coz_id,
        sch.sch_id, sch.sch_year, sch.sch_term, sch.sch_start_week, sch.sch_end_week,
        sch.sch_fortnight, sch.sch_day, sch.sch_start_time, sch.sch_end_time, sch.course_coz_id, sch.location_loc_id,
        loc.loc_id, loc.loc_name,
        coz.coz_id, coz.coz_name, coz.coz_size, coz.coz_act_size, coz.coz_att_rate,
        tea.user_usr_id tea_user_usr_id, tea.course_coz_id,
        tch.usr_name tea_user_usr_name,
        coz_sch.sch_id coz_sch_id, coz_sch.sch_year coz_sch_year, coz_sch.sch_term coz_sch_term,
        coz_sch.sch_start_week coz_sch_start_week, coz_sch.sch_end_week coz_sch_end_week, coz_sch.sch_fortnight
        coz_sch_fortnight,
        coz_sch.sch_day coz_sch_day, coz_sch.sch_start_time coz_sch_start_time, coz_sch.sch_end_time coz_sch_end_time,
        coz_sch.course_coz_id coz_sch_course_coz_id, coz_sch.location_loc_id,
        coz_sch_loc.loc_id coz_sch_loc_id, coz_sch_loc.loc_name coz_sch_loc_name,
        si_id, si_week, si_time, si_auto,
        sir_id, sir_time, sir_leave, sir_approve, sir_voucher, sir.sign_in_${curYear}_${curTerm}_si_id sir_id,
        sir.user_usr_id sir_user_usr_id
        FROM attendance att
        JOIN schedule sch ON att.course_coz_id = sch.course_coz_id
        LEFT OUTER JOIN location loc ON loc.loc_id = sch.location_loc_id
        <!-- sch coz -->
        JOIN course coz ON sch.course_coz_id = coz.coz_id
        LEFT OUTER JOIN teaching tea ON coz.coz_id = tea.course_coz_id
        LEFT OUTER JOIN schedule coz_sch ON coz.coz_id = coz_sch.course_coz_id
        LEFT OUTER JOIN location coz_sch_loc ON coz_sch.location_loc_id = coz_sch_loc.loc_id
        JOIN user tch ON tea.user_usr_id = tch.usr_id
        <!-- history sign in -->
        JOIN sign_in_${curYear}_${curTerm} si ON sch.sch_id = si.schedule_sch_id
        LEFT OUTER JOIN sign_in_rec_${curYear}_${curTerm} sir ON
        si.si_id = sir.sign_in_${curYear}_${curTerm}_si_id AND
        att.user_usr_id = sir.user_usr_id
        <where>
            sir.sir_id IS NULL <!-- 還沒(méi)簽到de  -->
                AND att.user_usr_id = #{usrId} <!-- 用戶id  -->
        </where>