What Cannot be a primary key?

Can 0 be a primary key?

Primary Key Can be Zero, but if you set Identity on the column it normally will start at 1 rather than Zero. Primary Key will have Identity Column ..

What is not true about primary key?

Primary key may not contain duplicate values. Primary Key is a combination of Unique and NOT NULL Constraints so it can't have duplicate values or any NULL values. A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records.

Can there be 3 primary keys?

A table can only ever have a one primary key. It is not possible to create a table with two different primary keys. You can create a table with two different unique indexes (which are much like a primary key) but only one primary key can exist.

Which key can be primary key?

A primary key, also called a primary keyword, is a key in a relational database that is unique for each record. It is a unique identifier, such as a driver license number, telephone number (including area code), or vehicle identification number (VIN). A relational database must always have one and only one primary key.