如何在php中獲取sql數據庫查詢的最大值

Question

我想根據電子郵件ID和用戶名找出sql數據列的最大值。 （沒有主要實體）要獲取電子郵件ID，我存儲了會話中的用戶電子郵件ID。

這是我的代碼：

$emailid = $userRow['emailid'];

$sql = "select max(item) from product where email = '$emailid' AND username = 'arun'";

$result = $conn-> query($sql);

$row = $result->fetch_assoc();
echo "Max item : " .$row['result'];

它給了我sql表的第一個值，但不是最高值。

Answer 1

您可以更改列數據類型，也可以使用CAST或CONVERT 。

$sql = "SELECT MAX( CAST( `item` AS UNSIGNED) ) as max FROM `product` WHERE `email` = '$emailid' AND `username` = 'arun'";

如果可能的話，最好更改數據類型。

Answer 2

嘗試這個，

$emailid = $userRow['emailid'];
$sql = "SELECT MAX(item) AS item FROM product WHERE email = '$emailid' AND username = 'arun'";
$result = $conn-> query($sql);
$row = $result->fetch_assoc();
echo "Max item : " .$row['item'];

Answer 3

試試這個

$rowSQL = mysql_query( "SELECT MAX( ID ) AS max FROM `tableName`;" );
$row = mysql_fetch_array( $rowSQL );
$largestNumber = $row['max'];