I actually figured out what I had done wrong now but I am having another issue that will undoubtably have a really simple answer making me feel quite stupid but here it goes anyway.
In Heidi SQL when you want to manipulate a value, you simply double click it and type in the new value, job done. However in DbVisualiser it doesn't seem to let me do this. I double click a field, I try typing in it when it's selected and I try right-clicking to see if there is an option to edit value but I really can't work it out.
Sorry for the noob question but any help would be appreciated or an alternative to DbVisualiser that I can use on mac.