Flat File Transformation

[sa0309]

I'm trying to determine the best method of transforming my source ( Flat file ) that has multipe fields to a 1 column target ( Oracle table ). I want to take the distinct values of Source.FIELD2 and insert into Target.FIELD1.

Source:
FIELD1 FIELD2 FIELD3 fIELD4
AAA 111 CCC DDD
AAA 123 DDDD EEE
BBB 456 E XXX
CCC 456 FF JJJ
zzz 123 DDDD EEE


Target:
FIELD1
111
123
456

Any best practice thoughts would be appreciated.

Thanks