Sql Union or Join or both together - mysql

Question

I have 2 tables AmountIn and AmountOut.
The first table Amountin looks like :
AmountIn
+--------+--------------+-----------+
| account| date | AmountIn |
+--------+--------------+-----------+
| A | 2017/2/6 | 200 |
| A | 2017/2/5 | 100 |
| A | 2017/2/5 | 500 |
| B | 2017/2/1 | 1000 |
| B | 2017/2/1 | 2000 |
| C | 2017/1/20 | 25 |
+--------+----+---------+-----------+
And the second one looks like:
AmountOut
+--------+--------------+-----------+
| account| date |AmountOut |
+--------+--------------+-----------+
| A | 2017/2/8 | 200 |
| A | 2017/2/7 | 100 |
| A | 2017/2/6 | 500 |
| B | 2017/2/2 | 1000 |
| B | 2017/2/1 | 2000 |
| C | 2017/1/20 | 25 |
+--------+----+---------+-----------+
Now I want a query that will display result as follow:
ForAccountA
+--------+--------------+----------+-----------+------------+
| account| date | AmountIn | AmountOut | Balancy |
+--------+--------------+-------- -+-----------+------------+
| A | 2017/2/5 | 500 | 0 | 500 |
| A | 2017/2/5 | 100 | 0 | 600 |
| A | 2017/2/6 | 0 | 500 | 100 |
| A | 2017/2/6 | 200 | 0 | 300 |
| A | 2017/2/7 | 0 | 100 | 200 |
| A | 2017/2/8 | 0 | 200 | 0 |
+--------+----+---------+----------+-----------+------------+
date field in the query is an union of date in both tables and the balancy is calculated as :
last balance + AmountIn - AmounOut

Answer 1

Try this:
select
t.*,
#sum := if(#account = account,
#sum + AmountIn - AmountOut,
if((#account := account) is not null,
AmountIn - AmountOut, 0)
) balance
from (
select
*
from (
select
1 x,
account,
date,
AmountIn,
0 AmountOut
from AmountIn
union all
select
0 x,
account,
date,
0 AmountIn,
AmountOut
from AmountOut
) t order by account, date, x
) t cross join (select #account := null, #sum := 0) t2
EDIT:
For three tables:
select
t.*,
#sum := if(#account = account,
#sum + amountOne + amountTwo - amountThree,
if((#account := account) is not null,
amountOne + amountTwo - amountThree, 0)
) balance
from (
select
*
from (
select
2 x, account, date, amount amountOne,
0 amountTwo, 0 amountThree
from table1
union all
select
1 x, account, date, 0 amountOne,
amount amountTwo, 0 amountThree
from table2
union all
select
0 x, account, date, 0 amountOne,
0 amountTwo, amount amountThree
from table3
) t order by account, date, x
) t cross join (select #account := null, #sum := 0) t2

Answer 2

MSSQL:
select ai.account,
ai.date,ai.AmountIn,
case when AmountIn is NULL then 0
else 0
end as AmontOut
from AmountIn as ai
where ai.account = 'A'
union
select ao.account,
ao.date,
case
when AmountOut is NULL then 0
else 0
end as AmountOut,
ao.AmountOut
from AmountOut as ao
where ao.account = 'A'
this returns your desired table without column balancy. Maybe someone help you out with this column

Answer 3

Select
case when a.account is not null
then a.account else b.account
end as Account,
case when a.account is not null then a.date
else b.date as date,
a.AmountIn, b.AmountIn, (a.AmountIn - b.AmountOut) as balance
from AmountIn
a left join ForAccontA on a.account = b.account where a.account = 'A' and
b.account = 'A'
Hi I would like to solve this query like this rather redundant code using union