Question

早上好，我有三个mysql表 transaction ， other_loan 和 payment 。我想对表事务中的列 load_amount 和 additional 求和，并将其对 other_loan 的列 amount 求和，然后减去到 payment 表中 payment_amount 列的总和。下面是我的代码：

$result = $db->query("
SELECT *
     , (sum(load_amount) + sum(additional) + sum(amount)) - sum(payment) as total 
  FROM transaction
     , other_loan
     , payment
  INNER JOIN client 
    ON client.id=transaction.id 
  INNER JOIN other_loan 
    ON other_loan.id=transaction.id 
  INNER JOIN payment 
    ON payment.id=transaction.id 
 INNER GROUP 
    BY client.id
  ");

这是我的桌子： transaction other_loan payment

我在表中显示结果，并且出现以下错误消息：

致命错误：未捕获错误：调用布尔值成员函数fetch_assoc（）

请帮助。谢谢。

Answer 1

查询失败（因此$result为布尔值false），因为您两次对JOIN和表other_loan和payment进行了{{1} JOIN运算符,），而不给它们加上别名。我怀疑您实际上并不想这样做，而您的查询应该看起来像这样：

$result = $db->query("SELECT *, (SUM(load_amount) + SUM(additional) + SUM(amount)) - SUM(payment) as total 
                      FROM transaction
                      INNER JOIN client ON client.id=transaction.id 
                      INNER JOIN other_loan ON other_loan.id=transaction.id 
                      INNER JOIN payment ON payment.id=transaction.id
                      GROUP BY client.id");

我还怀疑load_amount实际上应该是loan_amount。

求和并联接多个MySQL表

1 个答案: