如何从mysql数据库中查询两个表中的数据并显示一个HTML表

Question

I have two tables... Only $sql is executing. How do I get $sql2 to query also? $sql2 is storing the secondID with the current_timestamp in the database but not receiving any input from 'serialnumber.' Only the first $sql is querying and storing in the database.

       +--------------+
       | SafetyAtt    |       
       +--------------+             
       | SecondID    |
       | SerialNumber |
       +--------------+                    

          +---------+
          | Safety  |
          +---------+
          | ID      |
          | DateLog |
          | Topic   |
          +---------+

      <table>
        <thead>
        <tr align="left">
          <th>Seq</th>
          <th>Date</th>
          <th>Topic</th>
          <th># of Attendees</th>
          <th>Add Attendee</th>
        </tr>
        </thead>

    <?php
  $sql = "SELECT ID, DateLog, Topic FROM Safety";
  $sql2 = "SELECT secondID, SerialNumber FROM SafetyAtt";
  $result = $conn->query($sql);
  if (!$result) {
    trigger_error('Invalid query: ' . $conn->error);
  }

  if ($result->num_rows > 0) {
   // output data of each row
   while($row = $result->fetch_assoc()) {
    echo "<tr><td>" . $row["ID"]. "</td><td>" . $row["DateLog"] . "</td><td>"
    . $row["Topic"] . "</td><td>" . $row["secondID"] . "</td><td>"  ?>
      Serial Number: <input type="text" name="serialnumber" placeholder="Enter serial #"> <?php " . </td></tr>";
    }
    echo "</table>";
  } else {
   echo "0 results"; 
   }
  $conn->close();
    ?>

</table>

Answer 1

You have to JOIN your two tables and it should have one query. First you select the columns you want to get, then join the tables by using the foreign key or something else that is common in the two tables. For example,

"SELECT car.id, driver.name, driver.age FROM car INNER JOIN driver ON car.driverID=driver.driverID"

see this link to more about SQL JOINS.