underscores and joining tables

[Thomas Stieve]

Hello,

I have two tables which I want to join using primary keys that consists of titles. The title is the same in both tables, but one has underscores where there are spaces in the other table. I've tried to replace the underscore with a space. This appears to work visually, but I can't join them. They don't match. When I run a select query for underscores, the titles which I replaced the underscores are returned, even though it visually shows spaces. I have no clue what's happening.

Any help is much appreciated!
Tom