What data types can be primary keys?

Question

Data Type. Integer (number) data types are the best choice for primary key, followed by fixed-length character data types. SQL Server processes number data type values faster than character data type values because it converts characters to ASCII equivalent values before processing, which is an extra step.

Can a char be a primary key?

If an existing database table has a primary key column in which the values vary in length, but the type is CHAR instead of VARCHAR, the Application Server automatically trims any extra spaces when retrieving primary key values.

Can a string be a primary key?

Yes, from a performance standpoint (i.e. inserting or querying or updating) using Strings for primary keys are slower than integers. But if it makes sense to use string for the primary key then you should probably use it.

What are primary key examples?

A primary key is a column -- or a group of columns -- in a table that uniquely identifies the rows in that table. For example, in the table below, CustomerNo, which displays the ID number assigned to different customers, is the primary key.

Can a primary key be anything?

A primary key is not a special type of key. It is one of the keys of a table. If a table has only one key then a choice of primary key does not arise.

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