oracle學習筆記五

top-n 分析的語法: 

select [column_list], rownum  

from   (select [column_list] 

from table

order  by top-n_column)

where  rownum <=  n;

select empno,ename,job from

(select rownum rank,empno,ename,job from

(select empno,ename,job from emp order by empno)

where rownum<8

)where rank>3;

同義詞 同義詞是資料庫中乙個物件的別名,可以簡化對物件的訪問

create [public] synonym synonym

for    object;

public表示公用同義詞，如果沒有宣告則表示私有同義詞，公用同義詞是所有使用者都可以看到的同義詞，私有同義詞只有建立同義詞的使用者可以看到。

建立employees表的別名.

create synonym  s_emp

for  hr.employees;

刪除同義詞.

drop synonym s_emp;

oracle學習筆記五

top n 分析的語法 select column list rownum from select column list from table order by top n column where rownum n select empno,ename,job from select rownu...

oracle學習筆記五

top n 分析的語法 select column list rownum from select column list from table order by top n column where rownum n select empno,ename,job from select rownu...

Oracle學習筆記 五

組合集總計 group by with rollup cube grouping sets 子查詢按執行方式分 標準子查詢 關聯子查詢 標準子查詢 巢狀子查詢 標量值查詢 case with then 使用exits查詢 select user id,user name from tb 001 tb...