555-1 waitfor delay '0:0:0' --

That looks like a fragment of T-SQL (SQL Server) with a delay and a comment. Here’s what each part means:

• WAITFOR DELAY '0:0:0'

  • Tells SQL Server to pause the current batch for the given time: 0 hours, 0 minutes, 0 seconds.
  • Effect: effectively a no-op (no actual delay). If you used '00:00:05', it would pause for five seconds.

• -- at the end

  • In T-SQL, -- starts a comment. Everything after -- on that line is ignored.
  • Useful for commenting out the rest of the line or for adding notes.

• The leading "555-1"

  • This isn’t valid T-SQL by itself. In a script it might be a label, a line number, or part of a larger statement. On its own it would cause an error.

Example to illustrate:

• BEGIN PRINT 'start'; WAITFOR DELAY '00:00:05'; PRINT 'end'; END
• This would print "start", wait 5 seconds, then print "end".

If you’re studying for an exam, you might also see this in the context of time-based tests or SQL injection concepts, where WAITFOR DELAY can be used to infer information based on timing. The '0:0:0' version simply does nothing delay-wise.

Would you like a couple of quick practice questions or a short cheat-sheet on WAITFOR DELAY and related commands?