Lookup on the same file using the input file

I have a source file (say lookup.txt) which contains 6 ID Fields I need to do a lookup on the same file using the input file (say input.txt) having 1 ID in one row. I want to retreive the description of the records from the lookup.txt . Is there any function avaialble in DS to call repeatedly to do a lookup?

Note : [I][This question was asked by Manraj] [/I]

[QUOTE=JobHelper;7538]I have a source file (say lookup.txt) which contains 6 ID Fields I need to do a lookup on the same file using the input file (say input.txt) having 1 ID in one row. I want to retreive the description of the records from the lookup.txt . Is there any function avaialble in DS to call repeatedly to do a lookup?

Note : [I][This question was asked by Manraj] [/I][/QUOTE]

What does DS mean in your Que?
Is it Datastage?