How to SUM and SUBTRACT using SQL?

Question

I am using MySQL and I have two tables:

master_table

• ORDERNO
• ITEM
• QTY

stock_bal

Answer 1

I have tried this kind of technique. Multiply the subtract from data by (-1) and then sum() the both amount then you will get subtracted amount.

-- Loan Outstanding
    select  'Loan Outstanding' as Particular, sum(Unit), sum(UptoLastYear), sum(ThisYear), sum(UptoThisYear)
    from
    (
        select 
            sum(laod.dr) as Unit,
            sum(if(lao.created_at <= '2014-01-01',laod.dr,0)) as UptoLastYear,
            sum(if(lao.created_at between '2014-01-01' and '2015-07-14',laod.dr,0)) as ThisYear,
            sum(if(lao.created_at <= '2015-07-14',laod.dr,0)) as UptoThisYear
        from loan_account_opening as lao
        inner join loan_account_opening_detail as laod on lao.id=laod.loan_account_opening_id
        where lao.organization = 3
        union
        select
            sum(lr.installment)*-1 as Unit,
            sum(if(lr.created_at <= '2014-01-01',lr.installment,0))*-1 as UptoLastYear,
            sum(if(lr.created_at between '2014-01-01' and '2015-07-14',lr.installment,0))*-1 as ThisYear,
            sum(if(lr.created_at <= '2015-07-14',lr.installment,0))*-1 as UptoThisYear
        from loan_recovery as lr
        inner join loan_account_opening as lo on lr.loan_account_opening_id=lo.id
        where lo.organization = 3
    ) as t3