Restrict varchar() column to specific values?

Question

Is there a way to specify, for example 4 distinct values for a varchar column in MS SQL Server 2008?

For example, I need a column called Frequency (varchar) that onl

Answer 1

Personally, I'd code it as tinyint and:

• Either: change it to text on the client, check constraint between 1 and 4
• Or: use a lookup table with a foreign key

Reasons:

• It will take on average 8 bytes to store text, 1 byte for tinyint. Over millions of rows, this will make a difference.

• What about collation? Is "Daily" the same as "DAILY"? It takes resources to do this kind of comparison.

• Finally, what if you want to add "Biweekly" or "Hourly"? This requires a schema change when you could just add new rows to a lookup table.