Copy contents of a table based on text in a column, then insert it into another table

Question

I'm trying to write a MYSQLi statement that will copy contents of a table based on text in a column, then insert it into another table. I have a HTML button that is calling a php page. I'm using HTML5/PHP. Any help would be greatly appreciated.

Ex: Table1 - activitygenerate - Table Entries already exist Tabel2 - activity

In Table1:

INSERT INTO `activitygenerate`(`Description`, `StartTime`, `ActivityCompleted`, `DayofMonth`) VALUES ('Activity1', '12:00', '0', 'Sunday'),
('Activity2', '12:00', '0', 'Monday');

In Table2:

INSERT INTO `activity`(`processdate`, `Description`, `StartTime`, `ActivityCompleted` ) VALUES ('$date', 'Activity2', '12:00','0');

I know the syntax is wrong, but I'm not sure what it is supposed to be:

<?php
$con = mysqli_connect("localhost", "root", "");
$db = mysqli_select_db($con, 'activitesdb');

if(isset($_POST['generatelog']))
$date = date("Y-m-d", strtotime($_POST['date']));
$query = "INSERT INTO `activity` IF DayofMonth=`Monday` FROM `activitygenerate`";

$query_run = mysqli_query($con, $query);

  if($query_run)
  {
    echo '<script> alert("Data Saved"); </script>';
    header('Location: ../Daily-Activity-Log.php');
  }
  else {
    echo '<script> alert("Data not Saved"); </script>';
  }
?>

The result with combined Table1 & Table2:

<form action="includes/generatelog.php" method="post" enctype="multipart/form-data" name="generatelogform">
<button type="submit" name="generate">Generate Entries</button>
</form>

<table>
<tr>
<th>Process Date</th>
<th>Description</th>
<th>Start Time</th>
<th>Activity Completed</th>
</tr>
<tr>
<td>3/3/20</td>
<td>Activity2</td>
<td>12:00</td>
<td><input type="checkbox"></td>
</tr>
</table>

I found a fix:

<?php
if(isset($_POST['generatelog']))
{
  $date = date("Y-m-d", strtotime($_POST['date']));
  $day = date("l");

  if ($day == "Sunday"){
    $query = "INSERT INTO `activity` SELECT * FROM `activitygenerate` WHERE DayofWeek='1'";
    $everyday = "INSERT INTO `activity` SELECT * FROM `activitygenerate` WHERE DayofWeek='8'";
    $sql = "UPDATE `activity` SET `ProcessDate` = '$date' WHERE `activity`.`ProcessDate` = '0000-00-00'";
  }elseif ($day == "Monday"){
    $query = "INSERT INTO `activity` SELECT * FROM `activitygenerate` WHERE DayofWeek='2'";
    $everyday = "INSERT INTO `activity` SELECT * FROM `activitygenerate` WHERE DayofWeek='8'";
    $sql = "UPDATE `activity` SET `ProcessDate` = '$date' WHERE `activity`.`ProcessDate` = '0000-00-00'";
  }elseif ($day == "Saturday"){
    $query = "INSERT INTO `activity` SELECT * FROM `activitygenerate` WHERE DayofWeek='7'";
    $everyday = "INSERT INTO `activity` SELECT * FROM `activitygenerate` WHERE DayofWeek='8'";
    $sql = "UPDATE `activity` SET `ProcessDate` = '$date' WHERE `activity`.`ProcessDate` = '0000-00-00'";
  }else{
    $query = "INSERT INTO `activity` SELECT * FROM `activitygenerate` WHERE DayofWeek='8'";
    $sql = "UPDATE `activity` SET `ProcessDate` = '$date' WHERE `activity`.`ProcessDate` = '0000-00-00'";
  }

$query_run = mysqli_query($con, $query);
$query_update = mysqli_query($con, $sql);
$query_update_run = mysqli_query($con, $everyday);
?>