Question : What is primary key. Choose from the options given below -
Option 1: A Primary key is a field or a combination of fields that can uniquely identify a row/tuple in a table/relation.
Option 2: A Primary key in table/relation is any non-primary key field which also stores unique values for each row just like a primary-key does. But only one key is designated as primary key. So unique refers to a unique non-key field of a table.
Option 3: A Primary key is a field of a table which is the primary key of another table through a foreign key a relationship is established between two tables.
Option 4: None of the above
Correct Answer: A Primary key is a field or a combination of fields that can uniquely identify a row/tuple in a table/relation.
Solution : The column or columns that each row in a table uses to uniquely identify itself is known as the primary key. For Optim to insert, update, restore, or delete data from a database table, the table must contain a primary key.
Hence the correct answer is option 1.
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