Try this (I changed some of the data just to show 2 months)
jaggie@DEV>CREATE TABLE T5 (pk NUMBER, MONTH VARCHAR2(10), fld2 VARCHAR2(1), fld3 VARCHAR2(1), fld4 VARCHAR2(1))
2 /
Table created.
jaggie@DEV>INSERT INTO T5 VALUES (1,'Jan','B','C','D')
2 /
1 row created.
jaggie@DEV>INSERT...