Oracle: How query where datetime column not null and null values? - sql

Question

I want query datetime column not null and null values.
But i query have not null values now. i want query both values.
Query:
select l.com_code,
l.p_code,
to_char(l.effdate,'dd/mm/yyyy') effdate,to_char(l.expdate,'dd/mm/yyyy') expdate
from RATE_BILL l
where ( to_date('02/06/2016','dd/mm/yyyy') <= to_date(l.effdate,'dd/mm/yyyy')
or to_date('02/06/2016','dd/mm/yyyy') <= to_date(l.expdate,'dd/mm/yyyy') )
Data Sample
com_code | p_code | effdate | expdate
A | TEST01 | 01/01/2016 | 31/05/2016
A | Test01 | 01/06/2016 |
Query Result:
com_code | p_code | effdate | expdate
A | TEST01 | 01/01/2016 | 31/05/2016
A | Test01 | 01/06/2016 |
Column expdate If null = '31/12/9998' but show in DB is null
when query datetime = '02/06/2016' is between should result this
com_code | p_code | effdate | expdate
A | Test01 | 01/06/2016 |
But where query is
where ( to_date('31/05/2016','dd/mm/yyyy') <= to_date(l.effdate,'dd/mm/yyyy') or to_date('31/05/2016','dd/mm/yyyy') <= to_date(l.expdate,'dd/mm/yyyy') )
Result Should
A | TEST01 | 01/01/2016 | 31/05/2016
A | Test01 | 01/06/2016 |
Values Datetime is "Now Datetime"

Answer 1

First of all I must admit that I am not sure to understand the meaning of your text from your wording [no offence intended]. Feel free to comment if this answer does not address your needs.
The where condition of a query is built on the columns of the table/view and their sql data types. There is no need to convert datetime columns to the datetime data type.
Moreover, it is potentially harmful here since it implies an implicit conversion:
date column
-> char /* implicit, default format */
-> date /* express format;
in general will differ from the format the argument
string follows
*/
So change the where condition to:
where to_date('02/06/2016','dd/mm/yyyy') <= l.effdate
or to_date('02/06/2016','dd/mm/yyyy') <= l.expdate
To cater for null values, complement the where condition with 'sufficiently large' datetime to compare against in case of null values in the db columns:
where to_date('02/06/2016','dd/mm/yyyy') <= nvl(l.effdate, to_date('12/31/9998','dd/mm/yyyy'))
or to_date('02/06/2016','dd/mm/yyyy') <= nvl(l.expdate, to_date('12/31/9998','dd/mm/yyyy'))
You are free to use different cutoff dates. For example you might wish to use expdate from rate_bill when it is not null and the current datetime otherwise:
where to_date('02/06/2016','dd/mm/yyyy') <= nvl(l.effdate, to_date('12/31/9998','dd/mm/yyyy'))
or to_date('02/06/2016','dd/mm/yyyy') <= nvl(l.expdate, sysdate)

Answer 2

I don't understand the details of your problem, but I think you have got problems with comparison of null values.
Null values are ignored by comparison. To select these columns, you should explicitly check l.effdate is null
e.g.
-- select with expdate < today or with no expdate
select *
from RATE_BILL l
where l.expdate is null or
l.expdate <= trunc(sysdate)