Choose the correct option
cardholderphoneno
Answer 1Choose...not nulluniquecheckprimary key
creditcardtype should be silver or platinum only
Answer 2Choose...not nulluniquecheckprimary key
validitydate
Answer 3Choose...not nulluniquecheckprimary key
creditcardno
Answer 4Choose...not nulluniquecheckprimary key
cardholdername
Answer 5Choose...not nulluniquecheckprimary key
Answers
Answer:
cardholderphoneno - unique
creditcardtype should be silver or platinum only - check
validitydate- not null
creditcardno - primary key
cardholdername -not null
Explanation:
Answer:
- cardholderphoneno - unique
- creditcardtype should be silver or platinum only - check
- validitydate- not null
- creditcardno - primary key
- cardholdername -not null
Explanation:
In the relational model of databases, a number one secret's a selected preference of a minimum set of attributes (columns) that uniquely specify a tuple (row) in a relation (table).[a][1] Informally, a primary key is "which attributes pick out a report," and in easy cases constitute a single characteristic: a completely unique id. extra formally, a number one secret is a desire of candidate key (a minimal superkey); any other candidate key is an alternate key.
A primary key may additionally consist of real-global observables, wherein case it's miles called a natural key, even as an attribute created to characteristic as a key and not used for identity outside the database is called a surrogate key. for instance, for a database of humans (of a given nationality), time and place of delivery may be a natural key.[b] national identification number is some other example of an characteristic that may be used as a natural key.
In relational database phrases, a number one key does now not vary in form or feature from a key that isn't always number one. In practice, diverse motivations can also decide the selection of any person key as number one over every other. The designation of a primary key may suggest the "preferred" identifier for records in the table, or that the primary secret is for use for foreign key references from different tables or it could indicate some different technical in place of semantic feature of the desk. a few languages and software program have unique syntax functions that may be used to perceive a primary key as such (e.g. the number one KEY constraint in square).
The relational model, as expressed thru relational calculus and relational algebra, does not distinguish among primary keys and other sorts of keys. number one keys had been delivered to the square trendy specifically as a convenience to the application programmer.
Choose the correct option
https://brainly.in/question/40598250
What is the primary key?
https://brainly.in/question/4968582
#SPJ2