如果值爲空/空不顯示列/行

Question

我在顯示不同列數的不同表上使用的網頁上顯示SQL數據。對於具有空值的表，我不希望那些顯示在HTML表上。我如何創建它以便它們不顯示？

<?php 
    $sql1 = "SELECT * FROM lists WHERE id = $listid"; 

    $result1 = $mysqli->query($sql1); 
    while ($row = $result1->fetch_assoc()) { 
     $id = $row['id']; 
     $name = $row['name']; 
     $list_id = $row['list_id']; 
     $description = $row['description']; 
     $status = $row['status']; 
     $col1_name = $row['col1_name']; 
     $col2_name = $row['col2_name']; 
     $col3_name = $row['col3_name']; 
     $col4_name = $row['col4_name']; 
     $col5_name = $row['col5_name']; 
     $col6_name = $row['col6_name']; 
     $col7_name = $row['col7_name']; 
     $col8_name = $row['col8_name']; 
     $col9_name = $row['col9_name']; 
     $col10_name = $row['col10_name']; 
     $col11_name = $row['col11_name']; 
     $col12_name = $row['col12_name']; 
     $col13_name = $row['col13_name']; 
     $col14_name = $row['col14_name']; 
     $col15_name = $row['col15_name']; 
    } 

    // $id = $_GET["id"]; 
    $sql = "SELECT * FROM list_rows WHERE list_id = $listid"; 

    $result = $mysqli->query($sql); 

if ($result->num_rows) { 

    echo "<table class='w3-table-all' id='datatable'> 
    <thead> 
     <tr class='w3-indigo'>"; 
      if (!empty($row['col1_name'])){echo "<th>".$col1_name."</th>";} 
      if (!empty($row['col2_name'])){echo "<th>".$col2_name."</th>";} 
      if (!empty($row['col3_name'])){echo "<th>".$col3_name."</th>";} 
      if (!empty($row['col4_name'])){echo "<th>".$col4_name."</th>";} 
      if (!empty($row['col5_name'])){echo "<th>".$col5_name."</th>";} 
      if (!empty($row['col6_name'])){echo "<th>".$col6_name."</th>";} 
      if (!empty($row['col7_name'])){echo "<th>".$col7_name."</th>";} 
      if (!empty($row['col8_name'])){echo "<th>".$col8_name."</th>";} 
      if (!empty($row['col9_name'])){echo "<th>".$col9_name."</th>";} 
      if (!empty($row['col10_name'])){echo "<th>".$col10_name."</th>";} 
      if (!empty($row['col11_name'])){echo "<th>".$col11_name."</th>";} 
      if (!empty($row['col12_name'])){echo "<th>".$col12_name."</th>";} 
      if (!empty($row['col13_name'])){echo "<th>".$col13_name."</th>";} 
      if (!empty($row['col14_name'])){echo "<th>".$col14_name."</th>";} 
      if (!empty($row['col15_name'])){echo "<th>".$col15_name."</th>";} 


     echo "</tr> 
    </thead>"; 

    // output data of each row 
    echo "<tbody>"; 

    while($row = $result->fetch_assoc()) {  
     echo " 
     <tr class='w3-hover-pale-blue'>"; 
      if (!empty($row["col1_value"])){echo "<th>".$col1_value."</th>";} 
      if (!empty($row["col2_value"])){echo "<th>".$col2_value."</th>";} 
      if (!empty($row["col3_value"])){echo "<th>".$col3_value."</th>";} 
      if (!empty($row["col4_value"])){echo "<th>".$col4_value."</th>";} 
      if (!empty($row["col5_value"])){echo "<th>".$col5_value."</th>";} 
      if (!empty($row["col6_value"])){echo "<th>".$col6_value."</th>";} 
      if (!empty($row["col7_value"])){echo "<th>".$col7_value."</th>";} 
      if (!empty($row["col8_value"])){echo "<th>".$col8_value."</th>";} 
      if (!empty($row["col9_value"])){echo "<th>".$col9_value."</th>";} 
      if (!empty($row["col10_value"])){echo "<th>".$col10_value."</th>";} 
      if (!empty($row["col11_value"])){echo "<th>".$col11_value."</th>";} 
      if (!empty($row["col12_value"])){echo "<th>".$col12_value."</th>";} 
      if (!empty($row["col13_value"])){echo "<th>".$col13_value."</th>";} 
      if (!empty($row["col14_value"])){echo "<th>".$col14_value."</th>";} 
      if (!empty($row["col15_value"])){echo "<th>".$col15_value."</th>";} 
     echo "</tr>"; 
    } 
    echo "</tbody>"; 
    echo "</table>"; 
} else { 
    echo "0 results"; 
} 
echo "</div>"; 

//$mysqli->close(); 
?> 

我也試過：

if (!is_null($row['col1_name'])){echo "<th>".$col1_name."</th>";} 

和is_null，以及：

if ($row['col1_name'] != null){echo "<th>".$col1_name."</th>";} 

，沒有這些變化都工作過。它顯示一個空表或根本不顯示任何內容。

它顯示空列。如果這些列是空的，我不希望這些列出現。

col1_name | col2_name | col3_name | col4_name | col5_name | col6_name | col7_name | col8_name | col9_name | col10_name | col11_name | col12_name | col13_name | col14_name | col15_name | 
Item------| One_Day---| Three_Days | Ten_Days | Totals----| Notes-----| Facility--| Department| NULL------| NULL-------| NULL-------| NULL-------| NULL-------| NULL-------| NULL-------| 

數據庫中的數據

Answer 1

根據這個StackOverflow的職位（PHP: using empty() for empty string?），你不應該使用empty確定字串長度自變量存在本身。 empty最適合用於發生一些複雜情況的數組。

根據PHP documentation對於empty，以下情況將評估爲返回TRUE的empty。

以下的事情被認爲是空的：

• 「」（空字符串）
• 0（0作爲整數）
• 0.0（0爲float）
• 「 0" （0作爲字符串）
• NULL
• FALSE
• 陣列（）（空數組）
• $ var; （變量聲明，但沒有一個值）

因此，我比較反對一個空字符串：

if ($row['col1_name'] == ''){echo "<th>".$col1_name."</th>";}