how to include Null in "IN Condition" - sql

Question

I want to filter those employees with action_type with value 'Q' ,'R' or it can be null i.e. no action_type. I have used the old SQL syntax since this is the methodology followed in my firm.
I used "Union" in the query to include the null in the output too. But I think there can be a better and full proof way to do this
condition is :
AND ppa.action_type IN ( 'Q', 'R' )
SELECT *
FROM (SELECT DISTINCT papf.person_number,
name.first_name,
name.last_name,
paam.assignment_number,
py.payroll_name,
(SELECT meaning
FROM fnd_lookup_values
WHERE lookup_type LIKE 'ACTION_TYPE'
AND lookup_code = ppa.action_type
AND LANGUAGE = 'US'
AND enabled_flag = 'Y') ACTION_TYPE,
To_char(PPA.effective_date, 'DD-MON-YYYY')
EFFECTIVE_DATE,
ppa.payroll_action_id action_number
,
pcs.consolidation_set_name,
To_char(finc, 'DD-MON-YYYY') FINC,
pasv.user_status
FROM pay_assigned_payrolls_dn papd,
pay_payroll_terms pt,
pay_pay_relationships_dn pr,
pay_all_payrolls_f py,
per_all_people_f papf,
pay_payroll_actions ppa,
pay_consolidation_sets pcs,
per_person_names_f name,
pay_rel_groups_dn payrel,
per_all_assignments_m paam,
pay_payroll_rel_actions PPRA,
per_assignment_status_types_vl pasv,
pay_time_periods ptp,
per_legislative_data_groups_vl ldg
WHERE papd.payroll_term_id = pt.payroll_term_id
AND pt.payroll_relationship_id = pr.payroll_relationship_id
AND papd.payroll_id = py.payroll_id
AND pr.person_id = papf.person_id
AND ppa.payroll_id(+) = py.payroll_id
AND ptp.payroll_id = py.payroll_id
AND PPA.payroll_action_id(+) = PPRA.payroll_action_id
AND PPRA.payroll_relationship_id = pr.payroll_relationship_id
AND pasv.assignment_status_type_id =
paam.assignment_status_type_id
AND paam.assignment_type = 'E'
--ADDED condition---
AND pasv.user_status LIKE '%Payroll Eligible'
AND ( finc > ptp.start_date
OR finc IS NULL )
AND ppa.action_type IN ( 'Q', 'R' )
AND ldg.name = Nvl(:P_LEGISLATIVE_GROUP, ldg.name)
AND pasv.user_status = Nvl(:P_ASSIGNMENT_STATUS,
pasv.user_status)
AND To_char(Nvl(ppa.effective_date, SYSDATE), 'YYYY-MM-DD')
BETWEEN
To_char(Nvl(:p_from_date, SYSDATE), 'YYYY-MM-DD') AND To_char
(
Nvl(:p_TO_date, SYSDATE), 'YYYY-MM-DD')
-------
AND ldg.legislation_code = paam.legislation_code
AND ppa.consolidation_set_id(+) = pcs.consolidation_set_id
AND pcs.consolidation_set_id = py.consolidation_set_id
AND payrel.assignment_id = paam.assignment_id
AND payrel.group_type = 'A'
AND papf.person_id = name.person_id
AND name.name_type = 'GLOBAL'
AND payrel.parent_rel_group_id = papd.payroll_term_id
AND ppa.earn_time_period_id(+) = ptp.time_period_id
AND Nvl(ppa.effective_date, Trunc(SYSDATE)) BETWEEN
payrel.start_date AND payrel.end_date
AND Nvl(ppa.effective_date, Trunc(SYSDATE)) BETWEEN
papd.start_date AND papd.end_date
AND Trunc(SYSDATE) BETWEEN papf.effective_start_date AND
papf.effective_end_date
AND Trunc(SYSDATE) BETWEEN py.effective_start_date AND
py.effective_end_date
AND Trunc(SYSDATE) BETWEEN paam.effective_start_date AND
paam.effective_end_date
AND Trunc(SYSDATE) BETWEEN name.effective_start_date AND
name.effective_end_date
UNION
SELECT DISTINCT papf.person_number,
name.first_name,
name.last_name,
paam.assignment_number,
py.payroll_name,
(SELECT meaning
FROM fnd_lookup_values
WHERE lookup_type LIKE 'ACTION_TYPE'
AND lookup_code = ppa.action_type
AND LANGUAGE = 'US'
AND enabled_flag = 'Y') ACTION_TYPE,
To_char(PPA.effective_date, 'DD-MON-YYYY')
EFFECTIVE_DATE,
ppa.payroll_action_id action_number
,
pcs.consolidation_set_name,
To_char(finc, 'DD-MON-YYYY') FINC,
pasv.user_status
FROM pay_assigned_payrolls_dn papd,
pay_payroll_terms pt,
pay_pay_relationships_dn pr,
pay_all_payrolls_f py,
per_all_people_f papf,
pay_payroll_actions ppa,
pay_consolidation_sets pcs,
per_person_names_f name,
pay_rel_groups_dn payrel,
per_all_assignments_m paam,
pay_payroll_rel_actions PPRA,
per_assignment_status_types_vl pasv,
pay_time_periods ptp,
per_legislative_data_groups_vl ldg
WHERE papd.payroll_term_id = pt.payroll_term_id
AND pt.payroll_relationship_id = pr.payroll_relationship_id
AND papd.payroll_id = py.payroll_id
AND pr.person_id = papf.person_id
AND ppa.payroll_id(+) = py.payroll_id
AND ptp.payroll_id = py.payroll_id
AND PPA.payroll_action_id(+) = PPRA.payroll_action_id
AND PPRA.payroll_relationship_id = pr.payroll_relationship_id
AND pasv.assignment_status_type_id =
paam.assignment_status_type_id
AND paam.assignment_type = 'E'
--ADDED condition---
AND pasv.user_status LIKE '%Payroll Eligible'
AND ( finc > ptp.start_date
OR finc IS NULL )
AND ppa.action_type IS NULL
AND ldg.name = Nvl(:P_LEGISLATIVE_GROUP, ldg.name)
AND pasv.user_status = Nvl(:P_ASSIGNMENT_STATUS,
pasv.user_status)
AND To_char(Nvl(ppa.effective_date, SYSDATE), 'YYYY-MM-DD')
BETWEEN
To_char(Nvl(:p_from_date, SYSDATE), 'YYYY-MM-DD') AND To_char
(
Nvl(:p_TO_date, SYSDATE), 'YYYY-MM-DD')
-------
AND ldg.legislation_code = paam.legislation_code
AND ppa.consolidation_set_id(+) = pcs.consolidation_set_id
AND pcs.consolidation_set_id = py.consolidation_set_id
AND payrel.assignment_id = paam.assignment_id
AND payrel.group_type = 'A'
AND papf.person_id = name.person_id
AND name.name_type = 'GLOBAL'
AND payrel.parent_rel_group_id = papd.payroll_term_id
AND ppa.earn_time_period_id(+) = ptp.time_period_id
AND Nvl(ppa.effective_date, Trunc(SYSDATE)) BETWEEN
payrel.start_date AND payrel.end_date
AND Nvl(ppa.effective_date, Trunc(SYSDATE)) BETWEEN
papd.start_date AND papd.end_date
AND Trunc(SYSDATE) BETWEEN papf.effective_start_date AND
papf.effective_end_date
AND Trunc(SYSDATE) BETWEEN py.effective_start_date AND
py.effective_end_date
AND Trunc(SYSDATE) BETWEEN paam.effective_start_date AND
paam.effective_end_date
AND Trunc(SYSDATE) BETWEEN name.effective_start_date AND
name.effective_end_date)

Answer 1

There are two ways:
AND (action_type IN ('Q', 'R') OR action_type IS NULL)
or:
AND COALESCE(action_type, 'Q') IN ('Q', 'R')
Performance may or may not be better with one or the other depending on your particular situation.

Answer 2

How about or?
(ppa.action_type IN ( 'Q', 'R' ) or pa.action_type is null)

Answer 3

You can consider using Oracle spesific NVL function (NVL( value1, value2 ) replace value1 with value2 if value1 is null) briefly as
NVL( action_type, 'Q') IN ( 'Q', 'R' )
whenever action_type is null also, NVL( action_type, 'Q') matches with 'Q' which exists in the list within parentheses.