【2019年8月】OCP 071認證考試最新版本的考試原題-第18題

Choose two

Which two statements are true about the WHERE and HAVING clouses in a SELECT statement?

A) The WHERE clause can be used to exclude rows after divding them into groups

B) WHERE and HAVING clauses can be used In the same statement only if applied to dfferent table columns.

C) The HAVING clause can be used with aggregating functions in subqueries.

D) Aggregating functions and columns used in HAVING clauses must be spectfied in thes SELECT list of a query.

E) The WHERE clause can be used to exclude rows before dviding them into goups.

Answer：CE

(解析：having 子句是能夠跟子查詢進行配合使用，並且子查詢中也能夠有分組函數;

Oracle 先過濾再分組，照樣子能夠減小數據的處理數量;

D 檔案說在 having 子句中用到列必須出如今 select 子句中，這是不須要的。)