Join a query into another query with column computation - php

Question

I have three tables named issue_details, nature_payments, and rci_records. Now I have this query which joins this three tables.
SELECT issue_details.issue_date AS Date,
issue_details.check_no AS Check_No,
payees.payee_name AS Name_payee,
nature_payments.nature_payment AS Nature_of_Payment,
issue_details.issue_amount AS Checks_issued,
issue_details.nca_balance AS Nca_balance
FROM
issue_details
INNER JOIN
nature_payments ON
issue_details.nature_id = nature_payments.nature_id
INNER JOIN
payees ON
issue_details.payee_id = payees.payee_id
ORDER BY Date Asc, Check_no ASC
On my column in Nca_balance, this is a computed differences of every issuances of check. But you may not know what really the process of how I got the difference but to make it simple, let's say that I have another query
that dynamically get also the difference of this nca_balance column. Here is the query:
SELECT r.*,
(#tot := #tot - issue_amount) as bank_balance
FROM (SELECT #tot := SUM(nca_amount) as nca_total FROM nca
WHERE account_type = 'DBP-TRUST' AND
year(issue_date) = year('2015-01-11') AND
month(issue_date) = month('2015-01-11')
)
vars CROSS JOIN issue_details r
WHERE r.account_type = 'DBP-TRUST' AND
r.issue_date = '2015-01-11'
ORDER BY r.issue_date, r.check_no
I know it you may not get my point but I just want to replace the first query of the line
issue_details.nca_balance AS Nca_balance
with my own computation on my second query.
Please help me combine those two query into a single query. Thanks