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Oracle高級(jí)查詢

難度初級(jí)
時(shí)長(zhǎng) 3小時(shí)25分
學(xué)習(xí)人數(shù)
綜合評(píng)分9.63
123人評(píng)價(jià) 查看評(píng)價(jià)
9.8 內(nèi)容實(shí)用
9.6 簡(jiǎn)潔易懂
9.5 邏輯清晰
select * from (select * from emp order by sal desc)where rownum<=3這樣也是可以的
select p.ci_id,max(stu_name) as STU_NAME
from (select c.ci_id,wm_concat(s.stu_name)
over(partition BY c.stu_ids order by s.stu_id) as stu_name
from pm_ci c,pm_stu s
where instr(c.stu_ids,s.stu_id) > 0) p
group by p.ci_id

查詢出來(lái)后有排序效果的
是的說(shuō)的很對(duì)
你要說(shuō)where時(shí)還沒執(zhí)行分組我倒還能理解
講的生動(dòng)有趣,比較詳細(xì),謝謝老師
拿走,不謝,已測(cè)試通過(guò)
select t3.ci_id as CI_ID,
wm_concat(t3.stu_name) as STU_NAME
from
(
select t1.ci_id,t2.stu_name
from pm_ci t1 cross join pm_stu t2
where instr(t1.stu_ids,t2.stu_id)>0
) t3
group by t3.ci_id;
select ci_id,wm_concat(stu_name) stu_name
from pn_ci a,pm_stu b
where instr(stu_ids,stu_id)>0
group by ci_id;
專家講課,化繁為簡(jiǎn)
select c.ci_id,wm_concat(s.stu_name) stu_name
from pm_ci c left outer
join pm_stu s on c.stu_ids=s.stu_id
group by c.ci_id;
SELECT CI_ID,TO_CHAR(WM_CONCAT(STU_NAME)) STU_NAMES
FROM (SELECT * FROM PM_CI,PM_STU
WHERE INSTR(STU_IDS,STU_ID)<>0)
GROUP BY CI_ID
SELECT CI_ID,WM_CONCAT(STU_NAME) STU_NAMES
FROM (SELECT CI_ID,STU_NAME FROM PM_CI,PM_STU
WHERE INSTR(STU_IDS,STU_ID)<>0) GROUP BY CI_ID,結(jié)果是正確的,可是出現(xiàn)了一個(gè)問(wèn)題,STU_NAMES字段顯示(HUGECLOB),只有點(diǎn)開后面的省略號(hào)才能看到字符串值,求解答
--oracle 右連接
Select d.deptno,d.dname,Count(e.empno) from emp e,dept d
Where e.deptno(+) = d.deptno
Group By d.deptno,d.dname

--mysql 右連接
Select d.deptno,d.dname,Count(e.empno)
from emp e Right Join dept d On e.deptno= d.deptno
Group By d.deptno,d.dname
select deptno,listagg(ename,',') within group (order by deptno) enameList from emp group by deptno;
全課程學(xué)完了,方言會(huì)不少
課程須知
小伙伴們,學(xué)習(xí)本課程前需要掌握Oracle的語(yǔ)法基礎(chǔ),并且對(duì)Oracle的函數(shù)有所了解。如不了解這兩部分內(nèi)容,請(qǐng)移步《Oracle數(shù)據(jù)庫(kù)開發(fā)必備利器之SQL基礎(chǔ)》和《Oracle數(shù)據(jù)庫(kù)開發(fā)利器之函數(shù)》兩門教程。
老師告訴你能學(xué)到什么?
1、掌握分組查詢 2、掌握多表查詢 3、掌握子查詢

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