Hi,
Let me try to answer your questions.
Q1. Can we use Loop statement in field routine?
A1. You can use it if required. E.g. if you cannot use a READ statement using one or more key fields. Be aware that the field routine will process a single record and a single field at a time.
Q2. Does Field routine is for processing of only single record at a time? if yes, loop will also work the same way.
A2. Please see A1.
Q3. I actually replaced SELECTS SINGLE statement which is written in field routine with READ Statement but unfortunately, READ statement was not working so i replaced with LOOP Statement. So, IS it fine and will give me the same output similar to select single or read statement?
A3. Please see A1. The best practice is to read a single record from an internal table filled in the start routine with the READ statement. If it does not work (e.g. because of time-dependent data), you can use a LOOP statement.
If this general advice is not sufficient, please provide a concrete example and share the coding which you wrote so far.
Best regards,
Sander