hi,i want t0 knom d syntax for a super key with an example
Answer / 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 |
What is ms sql server triggers?
How to verify a user name with sqlcmd tool?
what is Data Transformation Services (DTS) ?can u explain me in detail?
How to use clusters?
how can i lock the column in the table
Please explain the characteristics of a transaction server for example atomicity, consistency, isolation, durability?
What is inline table-value user-defined function?
Explain primary key and foreign key constraints?
How many full-text indexes can a table have?
create index a on employee(dno) In this,which index was created?
How to retrieve duplicate rows in a table? How to delete the duplicate entries in a table?
15 Answers Leo Technologies, Mannar Company, Synechron,
Why are you getting errors when creating a new odbc dsn?