Арифметические операторы с предложением SELECT, LEFT JOIN и WHERE

Question

Мне нужна помощь. У меня есть код ниже, который отлично работает, но не достигает моей цели. Мне нужен столбец «account_title» с каждым из его вычисленных значений стороной перед вычитанием, которая должна в конечном итоге дать мне разницу вычитаемого значения. Спасибо в ожидании.

SELECT 
(
    SELECT SUM(amount) 
    FROM mainaccount_a_2017 
    LEFT JOIN chart_of_account ON (chart_of_account.joint_account_numbers = mainaccount_a_2017.joint_account_number) 
    LEFT JOIN asset_liability_income_expenditure_tbl ON (asset_liability_income_expenditure_tbl.a_l_code = chart_of_account.account_type) 
    WHERE a_l_code = 'FA' AND dr_cr_action = 'DR' 
) 
- 
(
    SELECT SUM(amount) 
    FROM mainaccount_b_2017 
    LEFT JOIN chart_of_account ON (chart_of_account.joint_account_numbers = mainaccount_b_2017.joint_account_number) 
    LEFT JOIN asset_liability_income_expenditure_tbl ON (asset_liability_income_expenditure_tbl.a_l_code = chart_of_account.account_type) 
    WHERE a_l_code = 'FA' AND dr_cr_action = 'CR' 
) 

Answer 1

Изменить подзапросы быть сгруппированы по account_title, а затем присоединиться к ним.

SELECT debits.account_title, debits.total - credits.total AS net_reduction 
FROM (
    SELECT mainaccount_a_2017.account_title, SUM(amount) AS total 
    FROM mainaccount_a_2017 
    LEFT JOIN chart_of_account ON (chart_of_account.joint_account_numbers = mainaccount_a_2017.joint_account_number) 
    LEFT JOIN asset_liability_income_expenditure_tbl ON (asset_liability_income_expenditure_tbl.a_l_code = chart_of_account.account_type) 
    WHERE a_l_code = 'FA' AND dr_cr_action = 'DR' 
    GROUP BY mainaccount_a_2017.account_title 
) AS debits 
JOIN (
    SELECT mainaccount_b_2017.account_title, SUM(amount) AS total 
    FROM mainaccount_b_2017 
    LEFT JOIN chart_of_account ON (chart_of_account.joint_account_numbers = mainaccount_b_2017.joint_account_number) 
    LEFT JOIN asset_liability_income_expenditure_tbl ON (asset_liability_income_expenditure_tbl.a_l_code = chart_of_account.account_type) 
    WHERE a_l_code = 'FA' AND dr_cr_action = 'CR' 
    GROUP BY mainaccount_b_2017.account_title 
) AS credits ON debits.account_title = credits.account_title 

DEMO