Select query from two tables

I have two tables a and b
column names are id and date.
Data type of date in a and b are different

table (a)

date id
10-DEC-01 2:08:39 PM 1
10-DEC-01 2:08:39 PM 2
10-JAN-02 10:10:22 PM 3
10-JAN-02 10:10:22 PM 4
10-JAN-02 10:10:22 PM 5


table (b)
date id
10-DEC-01 1
10-DEC-01 2



I need table b like this one
table (b)


date id
10-DEC-01 1
10-DEC-01 2
10-JAN-02 3
10-JAN-02 4
10-JAN-02 5


please help me!!!!

And what are the data types of those columns?