如何檢查MySQL結果是否為空

Question

    // 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結果返回空，我試圖回顯“無結果可顯示”。 問題是標題是作為數組的一部分返回的，我該如何實現呢？

Answer 1

您可以使用num_rows來獲取從查詢中檢索到的記錄的總值。

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

Answer 2

您需要檢查行數。 如果返回零，則表示表不包含任何行。 嘗試下面的代碼。

// 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>");

  }

}

Answer 3

簡單使用num_rows

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

Answer 4

您可以使用num_rows來獲取記錄的總值。

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