How do I only extract one instance of a certain field that appears in multiple logs of different formats?

[akhilchhugani]

If I have log files with multiple logs in them of different formats, and I only want to receive one instance of the Login_ID, though it occurs multiple times in the file in different logs, therefore they will all have the same sourcetype. I currently have the Login_Success_ID:1234545 in this format and want to use the field extractor to get this value because I only want the users that were able to log in, that is why I want one instance of the userid in the whole log file. Could someone explain how I could do this with the field extractor or if I need to change the format of the log file itself?

[woodcock]

Just create a field extraction that works and if it is creating multi-valued fields, use Login_Success_ID=mvindex(Login_Success_ID,0) to get the first one.