(setq indent-tabs-mode nil)

[ewx]

[Poll #959499]

(Ignoring languages like make where you don't have any choice.)

Comments

[hairyears.livejournal.com]

It depends whether the IDE does indentation by inserting spaces or a TAB character.

Now for the hard question: do you do tabs in SQL?

[sparrowsion]

If your editor can't be configured to your preference of spaces or tab, throw it away and get something from the current century.