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047-127

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-19 09:49:51 0 删除 编辑
127. Which statements are true regarding the usage of the WITH clause in
complex correlated subqueries?
(Choose all that apply.)
A. It can be used only with the SELECT clause.
B. The WITH clause can hold more than one query.
C. If the query block name and the table name were the same, then the table
name would take precedence.
D. The query name in the WITH clause is visible to other query blocks in the
WITH clause as well as to the main query block.
Answer: ABD
Precedence:优先
1: SQL> with
2 tt as(
3 select emp_no,enam
4 from emp
5 where mgr_no=4)
6 select ename
7 from tt
8 where emp_no=4;
Ok!
2: SQL> with
2 emp as(
3 select emp_no,ename
4 from emp
5 where mgr_no=4)
6 select ename
7 from emp
8 where emp_no=4;
ORA-32031: WITH 子句中查询名的引用非法

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