MYSQL LEFT JOIN INCORRECT RESULT

Question

我被困了很长时间而无法找到我的查询有什么问题，debit column LEFT JOIN出现了问题，Query Result image显示在debit table中，如下所示。我500的实际值为MYSQL，但1500查询显示为customers table。 我在这做错了什么。请帮助我。

这是我的cust_credit table

这是我的cust_debit table

这是我的MYSQL Query

SELECT customers.id as id, customers.cust_name AS customer_name, SUM(cust_debit.debit_amount) as debit, SUM(cust_credit.credit_amount) as credit, (SUM(cust_debit.debit_amount)) - (SUM(cust_credit.credit_amount)) as balance FROM customers LEFT JOIN cust_debit ON customers.id = cust_debit.cust_id LEFT JOIN cust_credit ON customers.id = cust_credit.cust_id GROUP BY customers.id ORDER BY customers.id 以下是

Query Result

我的$arrcount = ceil(count($requestarr['SelectionDetails'])/30); $init = 0; if (count($requestarr['SelectionDetails']) > 30) { $endt = 29; } else { $endt = count($requestarr['SelectionDetails']); } for ($i=0; $i < $arrcount; $i++) { $request['SelectionDetails'] = array_slice($requestarr['SelectionDetails'], $init, $endt); $init = $endt+1; if (count($requestarr['SelectionDetails']) > ($endt+30)) { $endt += 30; } else { $endt = count($requestarr['SelectionDetails']); } //call to endpoind and other code here.... } 以下是

Answer 1

信用表中有多行，这会在组之前产生多行，从而导致问题。如果您取出组并选择所有列，则可以看到此信息。

如果您在子联接中分组，则此问题消失，那么每个客户在分组之前都有一行。

SELECT 
  customers.id as id, 
  customers.cust_name AS customer_name,
  SUM(cust_debit.debit_amount) as debit,
  SUM(cust_credit.credit_amount) as credit,
  (SUM(cust_debit.debit_amount)) - (SUM(cust_credit.credit_amount)) as balance
FROM customers
LEFT JOIN cust_debit  ON customers.id = cust_debit.cust_id
LEFT JOIN (
  SELECT cust_id, sum(credit_amount) as credit_amount)
  from cust_credit
  group by cust_id
) cust_credit ON customers.id = cust_credit.cust_id
GROUP BY customers.id
ORDER BY customers.id