PHPは最初の行のみを挿入します

Question

このPHPコードは最初の行を挿入してからエラーを返します：非オブジェクト上のメンバ関数fetch_assoc（）を呼び出します。 助けてください。

$sqlquery = "SELECT * FROM shopcart WHERE UserID='$Useremail'"; 
    if(!$result = $db->query($sqlquery)) die ('Error getting Food Information ['.$db->connect_error.']'); 
    $result = $db->query($sqlquery); 

    while($row = $result->fetch_assoc()){ 
     //echo $row['name']; 
     $name= $row['name']; 
     $productid = $row['ProductID']; 
     $initialPrice = $row['InitialPrice']; 
     $qty = $row['Quantity']; 



     //insert into to ordereditems 
     $sql = "INSERT INTO ordereditems (OrderID, ProductName, ProductID, Quantity, SalesPrice) 
     VALUES ('$orderid', '$name', '$productid','$qty','$initialPrice')"; 
     if(!$result = $db->query($sql)) die('There was an error Processing Order Again [' . $db->error . ']'); 

    } 

Answer 1

ループの最後の行で$結果を上書きします。

if(!$result = $db->query($sql)) die('There was an error Processing Order Again [' . $db->error . ']'); 

は次のようになります。

if(!$result2 = $db->query($sql)) die('There was an error Processing Order Again [' . $db->error . ']'); 

Answer 2

挿入操作によって、$result変数が上書きされます。次のようないくつかの他の名前に変更します。あなたは中傷している

if(!$result2 = $db->query($sql)) die('There was an error Processing Order Again [' . $db->error . ']'); 

Answer 3

をご$result：

$sqlquery = "SELECT * FROM shopcart WHERE UserID='$Useremail'"; 
    if(!$result = $db->query($sqlquery)) die ('Error getting Food Information ['.$db->connect_error.']'); 
    $result = $db->query($sqlquery); 
    ^^^^^^--- your first query 

    if(!$result = $db->query($sql)) die('There was an error Processing Order Again [' . $db->error . ']'); 
     ^^^^^^-kill the first query result, replace with new result 

そして、あなたはsql injection attacksに対して脆弱であり、このコードのすべてが自明で置き換えることができることに注意してくださいシングルinsert into ... select from ...クエリ。

Answer 4

あなたはINSERTクエリでSELECTクエリから最初の結果を上書きしています。

$sqlquery = "SELECT * FROM shopcart WHERE UserID='$Useremail'"; 
if(!$result = $db->query($sqlquery)) die ('Error getting Food Information ['.$db->connect_error.']'); 
//$result = $db->query($sqlquery); // NOT NEEDED AS ALREADY EXECUTED AND ASSIGNED in the IF statement above 

while($row = $result->fetch_assoc()){ 
    //echo $row['name']; 
    $name= $row['name']; 
    $productid = $row['ProductID']; 
    $initialPrice = $row['InitialPrice']; 
    $qty = $row['Quantity']; 

    /* 
    instead of assigning these variables manually you could also use: 

    extract($row); 

    this would convert name, ProductID, InitialPrice and Quantity to local variables $name, $ProductID, $InitialPrice and $Quantity. However make sure the db result does not contain key "result" as it would overwrite your $result object again :) 
    */ 


    //insert into to ordereditems 
    $sql = "INSERT INTO ordereditems (OrderID, ProductName, ProductID, Quantity, SalesPrice) 
    VALUES ('$orderid', '$name', '$productid','$qty','$initialPrice')"; 

    //if(!$result = $db->query($sql)) die('There was an error Processing Order Again [' . $db->error . ']'); // this is what overwrites $result and the next while check throws an error you just got 
    if(!$db->query($sql)) die('There was an error Processing Order Again [' . $db->error . ']'); //here's the fixed version, $db->query for insert does not return an object but boolean (true/false) so no need to assign it to a $result variable 
}