【2019年8月版】ocp 071认证考试原题-凯发app官方网站

examine the description of the product_information table:------------------------------------------------------------------------prod_nane varcrar2 (10)which query retrieves the number of products with a null list price?b) select count(nvl( l.........【阅读全文】

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发布时间：2019-11-25 10:17:30

which three statements are true about sequences in a single instance orade database?b) two or more tables cannot have keys generated from the same sequence.d) a sequence can issue duplicate values.f) a sequence can only be dropped by a dba.(解析：虚拟可以一下子产生一组的数字缓存在.........

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发布时间：2019-11-25 09:40:24

which two statenents are tue about the count function?b) count (distinct inv_amt) returns the number of rows excluding rows containing dupicates and nulls in the inv_amt columnd) a select statement using the count function with a distinct keyword cannot have a where clause.answer：：bc.........

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发布时间：2019-11-20 09:59:00

which two statements are true about the results of using the intersect operator in compound queres?b) column names in each select in the compound query can be dfferent.d) the number of columns in each select in the compound query can be dfferent.answer：：bc......

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发布时间：2019-11-20 09:27:05

which three statements are true about a self join?b) it can be an outer join.d) it must be an equijoin.f) the on clause can be used.(解析：左连接其实就是左外连接，是不同的称呼而已，其结果都是一样的，ansi 语法有select emp.empno,emp.deptno,dept.deptno,dept.dnameselect emp.emp.........

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