如何解決這些錯誤警告：（）mysqli_query：，mysqli_num_rows（）預計參數1，mysqli_fetch_assoc（）預計參數1個

Question

它是示值誤差這樣的：

Warning: mysqli_query(): Couldn't fetch mysqli in C:\xampp\htdocs\kidstore\admin\init\dataconfig.php on line 94 

Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, null given in C:\xampp\htdocs\kidstore\admin\init\dataconfig.php on line 95 

Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given in C:\xampp\htdocs\kidstore\admin\add-category.php on line 142 

這裏是我的代碼：

// fetch all data from database for all category in display 
function select_categories($connectionStatus){ 
    $query = "SELECT * FROM `categories` WHERE parent = 0"; 
    $result = mysqli_query($connectionStatus, $query); 
    if(mysqli_num_rows($result) > 0){ 
     mysqli_close($connectionStatus); 
     return $result; 
    } 
    return false; 

} 

Answer 1

嗨的問題是在這條線

$result = mysqli_query($connectionStatus, $query); 

添加mysqli_error()

$result = mysqli_query($connectionStatus, $query) or die(mysqli_error($connectionStatus)); 

也在哪裏你的mysqli_connect()。 您query沒有執行這就是爲什麼你得到errors

如果一切OK，然後運行一次你$query在PHP和檢查它給出的結果還是不行。但在此之前請檢查您的connection。