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

A good rule of thumb that I've found is simply whether or not a table is growing rows as a project continues,

For instance:

On a project I'm working on, the original designers decided to include site permissions as columns in the user table.

So now, we are constantly adding more columns as new features are implemented on the site. obviously this is not optimal. A better solution would be to have a table containing permissions and a join table between users and permissions to assign them.

However, for other more archival information, or tables that simply don't have to grow or need to be cached/minimize pages/can be filtered effectively, having a large table doesn't hurt too much as long as it doesn't hamper maintenance of the project.

At least that is my opinion.