datagridview 2 table wrong output - vb.net

Question

Given the following code:
connection = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=consignacion.mdb;")
SQLStr = "Select buyer,balance,
(SELECT SUM(salesdb.total)
From salesdb
Where salesdb.buyer = buyerdb.buyer and
buydate=#buydate and
salesdb.total is not Null and
salesdb.total<>#sales ) As [paid]
From buyerdb where balance>#balance"
cmd = New OleDbCommand(SQLStr, connection)
cmd.Parameters.AddWithValue("#buydate", Form1.Lbldate2.Text)
cmd.Parameters.AddWithValue("#balance", 0)
cmd.Parameters.AddWithValue("#sales", 0)
And below the ouput:
name balance sales
BANAL 1000
BAYA 500
RICKY 350
GEN 0
CASH 0
BAGON 0
LOREY 0
TANIS 0 2250
DARWIN 0 345
GLEN 1000 4334
LITO 0 505
LIZA 0 460
CESS 350 984
LOUIE 0 280
YOLLY 0 832
GLENDA 0 170
JOSE 1000 2240
I want to get the followed output:
name balance sales
BANAL 1000
BAYA 500
RICKY 350
TANIS 0 2250
DARWIN 0 345
GLEN 1000 4334
LITO 0 505
LIZA 0 460
CESS 350 984
LOUIE 0 280
YOLLY 0 832
GLENDA 0 170
JOSE 1000 2240
i wanted to display all buyers with balance > 0
i wanted to display all buyer with sales/total >0 at a given date. (sometimes buyers dont have record of sales on a given date.
i don't want to display buyers with balance and sales/total is zero at the same time.

Answer 1

First, use an LEFT JOIN between buyerdb b and salesdb s on the buyer key, and perform a SUM() on these records according a GROUP BY command. It will display buyerdb rows (the left table) even if there are no corresponding salesdb rows:
SELECT b.buyer, b.balance, SUM(s.total) as total
FROM buyerdb b
LEFT JOIN salesdb s on (b.buyer = s.buyer AND s.buydate = #buydate)
GROUP BY buyer
Then, use this request as a nested one, and filtered to get only the rows you want:
SELECT t.buyer, t.balance, t.total
FROM
(
SELECT b.buyer, b.balance, SUM(s.total) as total
FROM buyerdb b
LEFT JOIN salesdb s on (b.buyer = s.buyer AND s.buydate = #buydate)
GROUP BY buyer
) t
-- Filter the rows you don't want (both zero balance and total)
WHERE balance > 0 or total > 0
Working SQL fiddle (should work with Access).