How to get separate fields data with IF() statement in single query - mysql

Question

I am trying to get the unpaid and partial amount separately in single query
select
if(i.status = 'unpaid', sum(i.total_amount), '') unpaid,
if(i.status = 'partial', sum(i.paid_amount), '') partial
from {CI}invoices i
where
i.customer_id = ? and
date(i.invoice_date) < '2014-01-01' and
i.status not like 'paid%'
But i am getting blank i think that is because i used '' in if statement, i also tried with
if(i.status = 'unpaid', sum(i.total_amount) as unpaid, sum(i.paid_amount) as paid)
which is wrong because i can't use as in IF() condition. Can anyone please help me to resolve this query or suggest any alternative way??

Answer 1

Try the following:
SELECT
SUM( IF(i.status = 'unpaid', i.total_amount, 0) ) unpaid,
SUM( IF(i.status = 'partial', i.paid_amount, 0) ) partial
FROM {CI}invoices i
WHERE
i.customer_id = ? AND
date(i.invoice_date) < '2014-01-01' AND
i.status IN ('unpaid', 'partial')

Answer 2

Give this a go:
select
sum(case when i.status = 'unpaid' then i.total_amount else 0 end) as unpaid,
sum(case when i.status = 'partial' then i.paid_amount else 0 end) as partial
from {CI}invoices i
where
i.customer_id = ? and
date(i.invoice_date) < '2014-01-01' and
i.status not like 'paid%'

Answer 3

You have to cross join table to itself to get paid and unpaid in the same row:
SELECT
sum(iu.total_amount) unpaid,
sum(ip.paid_amount) partial
FROM {CI}invoices iu
CROSS JOIN {CI}invoices ip
where
ip.customer_id = ? AND iu.customer_id = ? AND
date(ip.invoice_date) < '2014-01-01' AND date(iu.invoice_date) < '2014-01-01' AND
iu.status = 'unpaid' AND ip.status = 'partial'