Question

我需要一些帮助。我即将创建一个小型电子商店，我想为每个用户添加追踪历史。

我有这个，但它不能像我想的那样工作。

$sql="SELECT * FROM transactions INNER JOIN cds ON transactions.cdCode=cds.code WHERE usrId='$userId' ORDER BY transactionId";
$result=mysqli_query($conn,$sql);
if (mysqli_num_rows($result)==0)
    echo "No purchases";
echo "<table>";

while($row=mysqli_fetch_array($result))
{
    echo "<tr><td>".$row['transactionId']."</td>";
    echo "<td>".$row['name']."</td>";
    echo "<td>".$row['cdQuantity']."</td>";
    echo "<td>".$row['price']."</td>";
    echo "<td>".$row['tDate']."</td>";
    echo "<td>".$row['status']."</td></tr>";
}
echo "</table>";

sql文件：

CREATE TABLE transactions (
    transactionId varchar(255) NOT NULL,
    usrId INT NOT NULL,
    cdCode varchar(35),
    cdQuantity int,
    tDate text,
    status text,
    PRIMARY KEY(transactionId,usrId,cdCode),
    FOREIGN KEY(usrId) REFERENCES users(userId),
    FOREIGN KEY(cdCode) REFERENCES cds(code)
);

它打印的内容如下：

> purchaseId  cdName quantity price date status
> 1e963a1d  CdName  1   price   2015-12-12:14:08    Pending
> 1e963a1d  CdName      1   price   2015-12-12:14:08    Pending
> 1e963a1d  CdName      1   price   2015-12-12:14:08    Pending
> 1e963a1d  CdName  1   price   2015-12-12:14:08    Pending
> 1f2b8183  CdName  1   price   2015-12-12:14:20    Pending
> 1f2b8183  CdName      1   price   2015-12-12:14:20    Pending
> 1f2b8183  CdName      1   price   2015-12-12:14:20    Pending

我想通过purchaseId将购买分组到不同的表中，以计算每次购买的总成本。

Answer 1

您可以将GROUP BY与现有查询一起使用，例如

SELECT t.*, SUM(t.price) as total_price
FROM transactions t
INNER JOIN cds c ON t.cdCode = c.code 
WHERE t.usrId = '$userId' 
GROUP BY t.purchaseId
ORDER BY transactionId;

显示购买历史记录

1 个答案: