Change this line in your script -

Code:

date_gen DATE := $DATEGEN;

to this -

Code:

date_gen VARCHAR2(10) := '$DATEGEN';

(A)
Before you understand how you can assign a string to a DATE variable, you need to understand that it's not a good practice to do so. Because you are relying on Oracle's implicit conversion rules by doing so.
So instead of doing that, declare the variable as a string and assign a string to it.

(B)
Just stick in the variable in your INSERT statement.
Of course, if you follow (A), then you'll have to convert your variable (which is a string) to a date first.

Code:

VALUES($EMPNAME,$EMPID,TO_DATE(date_gen,'YYYY-MM-DD'));

TO_DATE => converts string to date
TO_CHAR => converts date to string

You are using TO_DATE to convert a DATE (the variable date_gen) to a DATE. Again, that's not a good practice.

tyler_durden

Note:
(Oracle actually allows a date to be converted to a date using the TO_DATE function; it's an unintended consequence of implicit conversion.)