问题和（）

Question

我有一个SQL查询

SELECT accounting.id, enclosure.time, enclosure.enc_id_, enclosure.txt, accounting.type_id, accounting.amount, accounting.invoice_id, invoice.invoice_id_, accounting.subaccountoff_id 
FROM $this->db.accounting accounting 
INNER JOIN $this->db.enclosure enclosure ON enclosure.id=accounting.enc_id 
LEFT JOIN $this->db.balance_accounting balance_accounting ON balance_accounting.accounting_id=accounting.id 
LEFT JOIN $this->db.invoice invoice ON invoice.id=accounting.invoice_id 
LEFT JOIN $this->db.book_enclosure book_enclosure ON book_enclosure.enc_id=enclosure.id 
WHERE accounting.group_id='".$_SESSION['gid']."' && (accounting.subaccount_id='$id' || accounting.subaccountoff_id='$id') && accounting.type_id <= 4 && book_enclosure.enc_id IS NULL 
ORDER BY enclosure.time DESC, enclosure.enc_id_ DESC 

当我在SELECT子句中添加SUM（）查询只返回一行？

这样的..

SELECT accounting.id, enclosure.time, enclosure.enc_id_, enclosure.txt, accounting.type_id, accounting.amount, accounting.invoice_id, invoice.invoice_id_, accounting.subaccountoff_id, SUM(balance_accounting.amount) AS amount_off 
FROM $this->db.accounting accounting 
INNER JOIN $this->db.enclosure enclosure ON enclosure.id=accounting.enc_id 
LEFT JOIN $this->db.balance_accounting balance_accounting ON balance_accounting.accounting_id=accounting.id 
LEFT JOIN $this->db.invoice invoice ON invoice.id=accounting.invoice_id 
LEFT JOIN $this->db.book_enclosure book_enclosure ON book_enclosure.enc_id=enclosure.id 
WHERE accounting.group_id='".$_SESSION['gid']."' && (accounting.subaccount_id='$id' || accounting.subaccountoff_id='$id') && accounting.type_id <= 4 && book_enclosure.enc_id IS NULL 
ORDER BY enclosure.time DESC, enclosure.enc_id_ DESC 

我也试图通过添加一组，但仍只返回一行

GROUP BY balance_accounting.accounting_id 

编辑：

现在我得到一个错误：列 'accounting_id' 不能为空

SELECT accounting.id, enclosure.time, enclosure.enc_id_, enclosure.txt, accounting.type_id, accounting.amount, accounting.invoice_id, invoice.invoice_id_, accounting.subaccountoff_id, balance_accounting.amount_off 
FROM $this->db.accounting accounting 
INNER JOIN $this->db.enclosure enclosure ON enclosure.id=accounting.enc_id 
LEFT JOIN (
    SELECT accounting_id, SUM(amount) AS amount_off 
    FROM $this->db.balance_accounting 
) balance_accounting ON balance_accounting.accounting_id=accounting.id 
LEFT JOIN $this->db.invoice invoice ON invoice.id=accounting.invoice_id 
LEFT JOIN $this->db.book_enclosure book_enclosure ON book_enclosure.enc_id=enclosure.id 
WHERE accounting.group_id='".$_SESSION['gid']."' && (accounting.subaccount_id='$id' || accounting.subaccountoff_id='$id') && accounting.type_id <= 4 && book_enclosure.enc_id IS NULL 
ORDER BY enclosure.time DESC, enclosure.enc_id_ DESC 

Answer 1

... 
LEFT JOIN (
    SELECT accounting_id, SUM(amount) AS amount_off 
    FROM $this->db.balance_accounting balance_accounting 
) ON balance_accounting.accounting_id=accounting.id 
... 

Answer 2

SELECT accounting.id, enclosure.time, enclosure.enc_id_, enclosure.txt, accounting.type_id, accounting.amount, accounting.invoice_id, invoice.invoice_id_, accounting.subaccountoff_id, IFNULL(SUM(balance_accounting.amount), 0) AS amount_off 
      FROM $this->db.accounting accounting 
      INNER JOIN $this->db.enclosure enclosure ON enclosure.id=accounting.enc_id 
      LEFT JOIN $this->db.balance_accounting balance_accounting ON balance_accounting.accounting_id=accounting.id 
      LEFT JOIN $this->db.invoice invoice ON invoice.id=accounting.invoice_id 
      LEFT JOIN $this->db.book_enclosure book_enclosure ON book_enclosure.enc_id=enclosure.id 
      WHERE accounting.group_id='".$_SESSION['gid']."' && (accounting.subaccount_id='$id' || accounting.subaccountoff_id='$id') && accounting.type_id <= 4 && book_enclosure.enc_id IS NULL 
      GROUP BY accounting.id 
      ORDER BY enclosure.time DESC, enclosure.enc_id_ DESC