Return NULL as 0 in variable

Grafana MySQL
,
1

I am trying to return NULL as 0 in variable, but its not working.
Below is the query:

Query 1:
(select ifnull(QTIB_REQ_, 0) as x
from qb_requisitions_all
where QTIB_REQ_ IN ($Req_disabled_WA) and
CLIENT___BENCH___NON_BILLABLE IN ( ‘Non Billable’, ‘Non-Billable’, ‘NonBillable’) and
DATEDIFF(CURDATE(),TARGET_FILL_DATE) < 2 and
DATEDIFF(CURDATE(),TARGET_FILL_DATE) > 0

   )

community
community1740×750 38.1 KB

Query 2: This query returns NULL as 0, but returns max value for non null condition. I tried removing max condition but it throws error.

select (select coalesce(max(QTIB_REQ_), 0) 
  from qb_requisitions_all 
 where QTIB_REQ_ IN ($Req_disabled_WA) 
   and CLIENT___BENCH___NON_BILLABLE IN ( 'Non Billable', 'Non-Billable', 'NonBillable') 
   and DATEDIFF(CURDATE(),TARGET_FILL_DATE) < 30 
   and DATEDIFF(CURDATE(),TARGET_FILL_DATE) > 0
   )