Which CREATE TABLE statement is valid?

A.
CREATE TABLE ord_details
(ord_no NUMBER(2) PRIMARY KEY,
item_no NUMBER(3) PRIMARY KEY,
ord_date DATE NOT NULL);

B.
CREATE TABLE ord_details
(ord_no NUMBER(2) UNIQUE, NOT NULL,
item_no NUMBER(3),
ord_date DATE DEFAULT SYSDATE NOT NULL);

C.
CREATE TABLE ord_details
(ord_no NUMBER(2) ,
item_no NUMBER(3),
ord_date DATE DEFAULT NOT NULL,
CONSTRAINT ord_uq UNIQUE (ord_no),
CONSTRAINT ord_pk PRIMARY KEY (ord_no));

D.
CREATE TABLE ord_details
(ord_no NUMBER(2),
item_no NUMBER(3),
ord_date DATE DEFAULT SYSDATE NOT NULL,
CONSTRAINT ord_pk PRIMARY KEY (ord_no, item_no));

Show Hint

← Previous question

Next question →

Leave a Reply 26

Mike

For option D: isn’t it incorrect since you cannot use SYSDATE as the DEFAULT Date value?

Miguel

It´s correct, because don´t have clause CHECK, and only doing inserts with default sysdate

elman

hi. But what is the problem with a ?

Eric Sacramento

They tried to created a compound primary key, but the syntax is not correct. Every table must have just one PK.

Correct way to create a compound PK.
CONSTRAINT ord_pk PRIMARY KEY (ord_no, item_no));

Eric Sacramento

They tried to created a compound primary key, but the syntax is not correct.

Correct way to create a compound PK.
CONSTRAINT ord_pk PRIMARY KEY (ord_no, item_no));

elman

does constraint word absent ?

user

A is incorrect: only one primary key allowed per table.

elman

yes yes yes sureeeee

abhishek

Why isnt B correct??
It is not necessary that each table has a primary key.

kongo

B is not correct because of that line:
ord_no NUMBER(2) UNIQUE, NOT NULL,
Unique + no null = PK 🙂

And because of that D is more valid answer.

user2

B is not correct because of the comma (,) typed between UNIQUE and NOT NULL.

Unique + not null does NOT indicates it is PK. The table does NOT have to have a PK. Just a simple syntax error (for having an extra comma)

john

y is not c is corect?

Alvin2201

You cannot designate the same column or combination of columns as both a primary key and a unique key.
http://docs.oracle.com/cd/B28359_01/server.111/b28286/clauses002.htm

This is because the primary key constraint implies the creation of a unique index. So you would create the same index on the same column(s) twice.

singh

john

c is also corect i think.??

KARTHIK B S

Thanks Alvin2201 for clarifying the doubt on indexing 🙂

rca ieftin

Pretty great post. I simply came across your weblog and planned to mention that I’ve really enjoyed surfing around your site posts. After all I’ll be subscribing with your rss feed and I am hoping you are submitting again soon!|
rca ieftin http://goo.gl/6GqA7S