Oracle Certificate Profession 1Z0-051-27

LuiseDalian發表於2014-05-10
Oracle
（27）Which two statements are true regarding tables?

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.

答案：（F）

解析：

--C(X) 具有預設值的列是可以插入null值的

CREATE TABLE t

(

  col1 NUMBER(2),

  col2 VARCHAR2(10) DEFAULT 'hello'

);

insert into t values(1, null);

scott@TESTDB11>select * from t;

      COL1 COL2

---------- ----------

         1

        

--E(X)，同一方案中不允許任何兩個物件具有相同的名稱

scott@TESTDB11>create synonym emp for hr.employees;

create synonym emp for hr.employees

               *

ERROR at line 1:

ORA-00955: name is already used by an existing object

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