OCP-1Z0-051-题目解析-第27题

27. Which two statements are true regarding tables? (Choose two.)

A. A table name can be of any length.

B. A table can have any number of columns.

C. A column that has a DEFAULT value cannot store null values.

D. A table and a view can have the same name in the same schema.

E. A table and a synonym can have the same name in the same schema.

F. The same table name can be used in different schemas in the same database.

Answer: EF

B：错误。字段最多为1000个

能够測试下

SQL> create table tt(id int);

表已创建。

SQL> edit
已写入 file afiedt.buf

  1  declare
  2  v_string varchar2(100);
  3  begin
  4  for i in 1..1000 loop
  5  v_string := 'alter table tt add col'||i||' int' ;
  6  execute immediate v_string;
  7  end loop ;
  8* end;
SQL> /
declare
*
第 1 行出现错误:
ORA-01792: 表或视图中的最大列数为 1000
ORA-06512: 在 line 6

C: 错误。default的值能够为NULL

F：在不同的schema下。表名能够同样。

正确