何时是使用SQL语句的正确时间“SELECT [results] FROM [tables] WHERE [conditions] FETCH FIRST [n] ROWS ONLY”

I'm not quite sure when selecting only a certain number of rows would be better than simply making a more specific select statement. I have a feeling I'm missing something pretty straight forward but I can't figure it out. I have less than 6 months experience with any SQL and it's been cursory at that so I'm sorry if this is a really simple question but I couldn't find a clear answer.I'm not quite sure when selecting only a certai