SQL Optimization: how many columns on a table?

Question

The current project that I\'m working on have table with 126 columns and the least that i saw is at least 50 columns. Should a table hold less columns per table or separate

Answer 1

Here are the official statistics for SQL Server 2005 http://msdn.microsoft.com/en-us/library/ms143432.aspx

Keep in mind these are the maximums, and are not necessarily the best for usability.

Think about splitting the 126 columns into sections. For instance, if it is some sort of "person" table you could have

Person ID, AddressNum, AddressSt, AptNo, Province, Country, PostalCode, Telephone, CellPhone, Fax

But you could separate that into Person ID, AddressID, PhoneID

Address ID, AddressNum, AddressSt, AptNo, Province, Country, PostalCode

Phone ID, Telephone, Cellphone, fax

In the second one, you could also save yourself from data replication by having all the people with the same address have the same addressId instead of copying the same text over and over.