ocp考试资料群：569933648 验证码：ocp OCP 12c 19c考试题库解析与资料群：钉钉群号：35277291
全部博文（487）
分类： Oracle
2019-11-25 09:40:24
choose two
Which two statenents are tue about the COUNT function?
A) It can only be used for NUMBER data types.
B) COUNT (DISTINCT inv_amt) returns the number of rows excluding rows containing dupicates and NULLs in the INV_AMT column
C) COUNT(*) returns the number of rows in a table including duplicate rows and rows containing NULLs in any column.
D) A SELECT statement using the COUNT function with a DISTINCT keyword cannot have a WHERE clause.
E) COUNT(inv_amt) returns the number of rows in a table including rows with NULL in the INV_AMT column.
Answer：：BC
(解析：count 对于 null 值是忽略的;可以与 where 一起使用。)
