Hi.
Pretty much the same way you would do without UC4: You pipe the sql file to your sql command line client. You can, however, do this in an OS job from within UC4, but this mostly makes sense if you have to do this task regularily.
If your SQL is supposed to run against a supported database for the SQL agent, you could also take the contents of the SQL file and paste it into an SQL job, if you had an SQL agent for UC4. However, this also only makes sense for repeat tasks and even then, I'd probably go with the piping to the sql command-line client.
Hth,
Carsten