how to use sql using sql in oracle

how to use sql using sql in oracle

how to use sql to convert the first table to second table in oracle
for the first table, it has three columns called Time, TotalUsers and
Department. For the Department column, it only has two types of values,
one is * another is null. I need to make TotalUsers with *
intoTotalUsersStar, and make TotalUsers with null into TotalUsersNull in
the second table. Please see the second table.
First Table:
Date TotalUsers Department
199905 1234 *
199912 2345 *
200005 8923 (null)
200012 6783 (null)

Second table:
Date TotalUsersNull TotalUsersStar
199905 1234
199912 2345
200005 8923
200012 6783