顯示消息如果NUM_ROWS = 0從mysqli的準備語句

Question

我有試圖從在PHP一份聲明中查詢得到的行數的問題

，我的查詢看起來如下PHP：

$DBH = getDBH(); 
$stmt = $DBH->prepare("SELECT info FROM list WHERE tag = ?"); 
$stmt->bind_param("s",$tag); 
$stmt->execute(); 
$stmt->bind_result($information); 

和我基本上只是想說，如果沒有結果返回顯示「沒有結果返回」任何人都可以請幫忙嗎？

Answer 1

您需要使用$statement->store_result()第一。使用代碼：

$DBH = getDBH(); 
$stmt = $DBH->prepare("SELECT info FROM list WHERE tag = ?"); 
$stmt->bind_param("s",$tag); 
$stmt->execute(); 
$stmt->store_result(); 
$num_rows = $stmt->num_rows; 
$stmt->bind_result($information); 

Answer 2

我不承認你使用了類，但一般我這樣做：

$sql = "SELECT * FROM dummy WHERE category=13"; 
$result = mysql_query($sql); 
if(mysql_num_rows($result)>0) { 
// execute for positive results 
} else { 
// execute for 0 rows returned. 
} 

Answer 3

$sql = "SELECT * FROM dummy WHERE category=13"; 
$result = mysqli_query($link, $sql); 
$numrows=mysqli_num_rows($result) 
if($numrows>0) { 
// execute for positive results 
} else { 
// execute for 0 rows returned. 
}