Structure of the PROMOTION table

-Which of the following commands will add a UNIQUE constraint to the MINRETAIL column of the PROMOTION table?
A) ALTER TABLE promotion ADD CONSTRAINT orderitems_minretail_uk UNIQUE (minretail);
B) ALTER TABLE promotion MODIFY UNIQUE (minretail);
C) ALTER TABLE promotion ADD UNIQUE minretail;
D) ALTER TABLE promotion MODIFY minretail;

Question

​Structure of the PROMOTION table
 
-Which of the following commands will add a UNIQUE constraint to the MINRETAIL column of the PROMOTION table?​
A) ALTER TABLE promotion ADD CONSTRAINT orderitems_minretail_uk UNIQUE (minretail); 
B) ALTER TABLE promotion MODIFY UNIQUE (minretail); 
C) ALTER TABLE promotion ADD UNIQUE minretail; 
D) ​ALTER TABLE promotion MODIFY minretail;

Quizplus · Accepted Answer

The correct syntax to add a UNIQUE constraint to a column is "ADD CONSTRAINT UNIQUE ()". Option A follows this syntax and specifies the column name and the constraint name as "orderitems_minretail_uk". Option B is incorrect because it uses the keyword "MODIFY" instead of "ADD CONSTRAINT". Option C is incorrect because it doesn't specify the constraint name. Option D is incorrect because it also uses the keyword "MODIFY" instead of "ADD CONSTRAINT".

​Structure of the PROMOTION Table

Structure of the PROMOTION Table