如何检查 MySQL 结果是否为空 - How to check if a MySQL result is empty

How to check if a MySQL result is empty

    // Populate headers
    $fields = $result->fetch_fields();
    foreach ($fields as $field)
        printf("<th>%s</th>", $field->name);
    printf("</tr>");
    // Write to table
    while ($myvar = $result->fetch_row()) {
        $date = $myvar[0];
        $room_ID = $myvar[1];
        $description = $myvar[2];
        $firstname = $myvar[3];
        $lastname = $myvar[4];
        $message = $myvar[5];
        $period = $myvar[6];
        printf("<tr>");
        printf("<td>%s</td><td>%s</td>", $date, $room_ID);
        printf("<td>%s</td><td>%s</td>", $description, $firstname);
        printf("<td>%s</td><td>%s</td><td>%s</td>", $lastname, $message, $period);
        printf("</tr>");
  }

如果我的 MySQLi 结果返回空，我正在尝试回显"没有要显示的结果"。问题是标头作为数组的一部分返回，我该如何实现？

您需要检查行数。如果它返回零，则表示表不包含任何行。试试下面的代码。

// Populate headers
    $fields = $result->fetch_fields();
    foreach ($fields as $field)
        printf("<th>%s</th>", $field->name);
    printf("</tr>");
    // Write to table
    if($result->num_rows== 0){
     echo "No Result to display";
    }else{
    while ($myvar = $result->fetch_row()) {
        $date = $myvar[0];
        $room_ID = $myvar[1];
        $description = $myvar[2];
        $firstname = $myvar[3];
        $lastname = $myvar[4];
        $message = $myvar[5];
        $period = $myvar[6];
        printf("<tr>");
        printf("<td>%s</td><td>%s</td>", $date, $room_ID);
        printf("<td>%s</td><td>%s</td>", $description, $firstname);
        printf("<td>%s</td><td>%s</td><td>%s</td>", $lastname, $message, $period);
        printf("</tr>");
  }

}

简单使用num_rows

  if($result->num_rows== 0){
 echo "no results to display"
  }
else{
  while ($myvar = $result->fetch_row()) {
  //Your Code here
 }

您可以使用

num_rows来获取记录的总值。

$row_count = $result->num_rows;
if($row_count>0)
{ 
    echo "Data Available";
}
else
{
    echo "No Data Available";
}

可以使用

num_rows获取从查询中检索的记录的总值。

$row_cnt = $result->num_rows;
if($row_cnt>0){ echo "Have data";}else{echo "No data";}