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The field or combination of fields, the latter is called a composite key, which uniquely identifies a record. Often people use an integer automatically assigned at record creation, however, if possible it is best, to try for a field which is a unique attribute of the entity a table is describing.
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What is the primary key field in a database?
what is a Absolute reference
What is the primary key field of a database?
its a unique key use to identify data in database
Does the data in a primary key field common to all records?
Yes
When would you use a Primary Key and when would you not?
A primary key is a key that is unique. A primary key is used to identify a record uniquely. There is not any particular case to not have a primary key . If you want to identify your records you should have a primary key or a surrogate key(as an alternative to it) .In reality, you should always have a primary key. A primary key is there to uniquely identify each record, as it is like other elements would be duplicated. If you had a very large amount of names of people, then it is highly likely that the same firstname or same surname or even the same full name will come up more than once. Having a primary key distinguishes them as each primary key has to be unique.Situations where you might not use it is where you have a very defined set of values where there is guaranteed to be no duplicates, like a database that has the 12 months of the year or a list of regions that all have different names. You still could make them primary keys, but in the case of the months, it would change them into alphabetical order, which you would not want, so that would be another reason for not using a primary key. To keep them in order, you could add another field, with the values from 1 to 12 and use that field as the primary key.
Can two records have the same value in the primary key field?
Two records must not have the same value in the primary key field, as this would place them in the same ranking on the status sheet, which could result in a catastrophic failure of the desired program.
