[vog]

By the way, another related anti-pattern is the introduction of an additional table that has a 1:1 relationship to the original table. Because the original table was "full" of columns, or something, so a second table had to be opened to contain the remaining columns.

This is an anti-pattern because you can't model "1:1" that way. Instead, it will be "1:0..1", and now you have some nasty corner cases when the first table has an entry whose counterpart in the second table is missing. Also, when using a column now you always have to think about which table had it - the first or the second table?

I had to work with such a design in a real-world project and it was really annoying.

[simcop2387]

The way I have seen for the issue of which table is to introduce a view and setup triggers on the view to run a stored proc when you insert or update it to handle all the tables....

[paulddraper]

Ick. I use 1:0..1 tables commonly. But not 1:1. Ick.