How to create another Column in script

[#1]

I have this table,

TYPE	DATE_01	DATE_02
A	Type A	Type B
B	Type A	Type B
A	Type A	Type B
B	Type A	Type B
B	Type A	Type B
B	Type A	Type B
A	Type A	Type B
A	Type A	Type B

and i want to create a new column DATE_03 when if ([TYPE]="A";[DATE_01];[DATE_02])

This would result table

TYPE	DATE_01	DATE_02	DATE_03
A	Type A	Type B	Type A
B	Type A	Type B	Type B
A	Type A	Type B	Type A
B	Type A	Type B	Type B
B	Type A	Type B	Type B
B	Type A	Type B	Type B
A	Type A	Type B	Type A
A	Type A	Type B	Type A

[sunny_talwar]

May be this:

LOAD TYPE,

          DATE_01,

          DATE_02,

          If(TYPE = 'A', DATE_01, DATE_02) as DATE_03

FROM source;