查询使用mysqli在php中无法正常工作

 **DELETE.PHP**

<?PHP
include("db.PHP");
$id = $_GET['id'];
$check=MysqLi_query($conn,"SELECT * FROM details WHERE id='$id'");
while($row = MysqLi_fetch_array($check))
{
   $sub=$row['sub'];
   $quan=$row['quan'];
}
$check1=MysqLi_query($conn,"SELECT * FROM instock WHERE s_brand=$sub");
while($row1 = MysqLi_fetch_array($check1))
{
    $qty1=$row1['qty'];
}
$check2=MysqLi_query($conn,"SELECT * FROM outstock WHERE s_brand=$sub");
while($row2 = MysqLi_fetch_array($check2))
{
    $qty2=$row2['qty'];
}
$test2=MysqLi_query($conn,"UPDATE instock SET qty =$qty1+$quan WHERE 
s_brand='$sub'");
$test3=MysqLi_query($conn,"UPDATE  outstock SET qty =$quan-$qty2 WHERE 
s_brand='$sub'");
$result = MysqLi_query($conn, "DELETE FROM details WHERE id=$id");
header("Location:add_sale.PHP");
?>

这是我的delete.PHP文件
 删除查询工作正常.但是两个更新查询工作错误.它只是从$quan设置了数量.
      我需要马上
      提前致谢.

解决方法:

在你的第二个和第三个SELECT语句中,我认为你可能需要在$sub周围添加单引号,所以它们将是：

$check1=MysqLi_query($conn,"SELECT * FROM instock WHERE s_brand='$sub'");

和

$check2=MysqLi_query($conn,"SELECT * FROM outstock WHERE s_brand='$sub'");