hi,i want t0 knom d syntax for a super key with an example
Answer Posted / shikha
PersonID
PersonID + LastName
PersonID + FirstName
PersonID + DOB
PersonID + LastName + FirstName
PersonID + LastName + DOB
PersonID + FirstName + DOB
PersonID + LastName + FirstName + DOB
LastName + FirstName + DOB
All of these will uniquely identify each record, so each
one is a superkey. Of those keys, a key which is comprised
of more than one column is a composite key; a key of only
one column is a simple key.
A candidate key is a superkey that has no unique subset; it
contains no columns that are not necessary to make it
unique. This table has 2 candidate keys:
PersonID
LastName + FirstName + DOB
Not all candidate keys make good primary keys: Note that
these may work for our current data set, but would likely
be
.
| Is This Answer Correct ? | 3 Yes | 1 No |
Post New Answer View All Answers
What are null values in ms sql server?
what is the difference between Tabular and Matrix report?
Can the “if update (colname)” statement be used in a delete trigger?
How to disable triggers using "disable trigger"?
What are blobs, tables, and Queues? Is SQL is the standard way to query blobs, tables, and queues?
What is command parameter in ssrs?
Explain what is use of dbcc commands?
How can you append an identity column to a temporary table?
What according to you is the difference between mysql and sql server performance?
Explain nested trigger in sql?
you added a row to a view, but the row is not shown on the view. Explain how this can happen, and how you can remedy the situation
What is the difference between a "where" clause and a "having" clause?
What is policy management?
Explain how you can deploy an SSRS report?
what are different types of backups available in sql server? Given a particular scenario, how would you go about choosing a backup plan? : Sql server database administration