A table must have _____ ?a.Secondary keyb.Sort keyc.Composite keyd.Primary key
Question
A table must have _____ ?a.Secondary keyb.Sort keyc.Composite keyd.Primary key
Solution
A table must have a Primary key.
Here's why:
A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records. It has the following attributes:
- A primary key cannot contain NULL values.
- Each table has one primary key.
- A primary key uniquely identifies a record in the relational database table.
- It can either be a normal attribute that is guaranteed to be unique (such as Social Security Number in a table with no more than one record per person
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