每次顾客购买某样东西时,它都会出现在"purchase "表中,并获得一个新的"id"。
我现在想做一个mySQL查询,我可以在PHP上运行,这样做:
-
选择"购买"表的最后一行,从而识别最后一次购买的客户。
-
连接到"客户"表,并显示该客户的购买计数。
我使用这个代码,但它显示了每个客户的购买数量,而不仅仅是我想要的最后一个。
$mysqli = NEW MySQLI ('servername', 'username', 'password', 'dbname');
$resultSet = $mysqli->query ("SELECT quantity FROM customers INNER JOIN purchases ON customers.customer=purchases.customer");
if($resultSet->num_rows != 0){
while($rows = $resultSet->fetch_assoc())
{ $count = $rows['quantity'];
echo "<p>Number of purchases: $count";
}}
试试这个查询:
SELECT quantity FROM customers
WHERE customer= (select distinct customer
from purchases where
id = (select max(b.id) from purchases as b))