Multiple select checkbox to display the table record - php

Question

I want to filter the table by using multiple select checkbox by selecting multiple Company Name and the table will display the record related to the selected checkbox. It only able to select one checkbox and display one related record only but it cannot multiple select checkbox.
<form name="frmSearch" id="frmSearch" method="post" action="">
<label>Company Name </label>
<select id="multiple-checkboxes" multiple="multiple" name="COMPANYNAME">
<?php
$query = mysqli_query($conn_connection, "SELECT * FROM sl_iv GROUP by COMPANYNAME");
while ($row = mysqli_fetch_assoc($query)) {
echo "<option value='".$row["COMPANYNAME"]."'".($row["COMPANYNAME"]==$_POST["COMPANYNAME"] ? " selected" : "").">".$row["COMPANYNAME"]."</option>";
}
?>
</select>
<br></br>
<button type="submit" id="submit" class="btn btn-info btn-sm"><span class="glyphicon glyphicon-search"></span> Search</button>
<a href="cust_due_list.php">
<button type="button" class="btn btn-success btn-sm"><span class="glyphicon glyphicon-refresh"></span> RESET</button>
</a>
<br></br>
<table id="table">
<center>
<thead>
<tr class="item-row">
<th width="15%" style="text-align:center"><span>Doc No.</span></th>
<th width="10%" style="text-align:center"><span>Due</span></th>
<th width="5%" style="text-align:center"><span>Age</span></th>
<th width="20%" style="text-align:center"><span>Customer Name</span></th>
<th width="10%" style="text-align:center"><span>Ammount</span></th>
<th width="10%" style="text-align:center"><span>Payment</span></th>
<th width="10%" style="text-align:center"><span>OutStanding</span></th>
</tr>
</thead>
</center>
<tbody>
<?php
if(isset ($_POST['COMPANYNAME']))
{
$COMPANYNAME = $_POST['COMPANYNAME'];
$fetch = "SELECT sl_iv.DOCDATE, ar_iv.DUEDATE, payment_terms.terms, sl_iv.DOCNO, sl_iv.COMPANYNAME, ar_iv.DOCAMT, ar_iv.PAYMENTAMT FROM `sl_iv` Inner Join `ar_iv` On ar_iv.DOCNO = sl_iv.DOCNO Inner Join `payment_terms` On ar_iv.TERMS = payment_terms.id WHERE sl_iv.COMPANYNAME = '".$COMPANYNAME."' or sl_iv.DOCDATE <= '".$from."'";
$result = mysqli_query($conn_connection,$fetch)or die("MySQL error: " . mysqli_error($conn_connection) . "<hr>\nQuery: $fetch");
}
if (mysqli_num_rows($result) > 0) {
// output data of each row
while($row = mysqli_fetch_assoc($result)) {
$docamt = $row['DOCAMT'];
?>
<tr class="item-row">
<td>
<input type="text" style="text-align:center; font-size:15px" class="form-control input-sm DocNo" id=DocNo0 " name="DocNo " value="<?php echo htmlspecialchars($row[ 'DOCNO']);?>" readonly></td>
<td>
<input type="text" style="text-align:center; font-size:15px" class="form-control input-sm DueDate" id="DueDate0" name="DueDate" value="<?php echo htmlspecialchars($row['DUEDATE']);?>" readonly>
</td>
<td>
<input type="text" style="text-align:center; font-size:15px" class="form-control input-sm DateAge" id="DateAge0" name="DateAge" value="<?php echo $dateage;?>" readonly>
</td>
<td>
<input type="text" style="text-align:center; font-size:15px" class="form-control input-sm CompanyName" id="CompanyName0" name="CompanyName" value="<?php echo htmlspecialchars($row['COMPANYNAME']);?>" readonly>
</td>
<td>
<input type="text" style="text-align:right; font-size:15px" class="form-control input-sm TotalAmt" id="TotalAmt0" name="TotalAmt" value="<?php echo htmlspecialchars($row['DOCAMT']);?>" readonly>
</td>
<td>
<input type="text" style="text-align:right; font-size:15px" class="form-control input-sm payment" id="payment0" name="payment" value="<?php echo htmlspecialchars($row['PAYMENTAMT']);?>" readonly>
</td>
<td>
<input type="text" style="text-align:right; font-size:15px" class="form-control input-sm Total_Outstanding" id="Total_Outstanding0" name="Total_Outstanding" value="<?php echo number_format((float)$outstanding, 2, '.', '');?>" readonly>
</td>
</tr>
<?php
}
} else {
echo "0 results";
}
?>
</tbody>
</table>
</form>
<script type="text/javascript">
$(document).ready(function() {
$('#multiple-checkboxes').multiselect();
});
</script>

Answer 1

When you receive multiple-select POST it cames as array, so you should use "IN" operator in your mysql request instead of comparison.
Try to change one part of your code:
if(isset ($_POST['COMPANYNAME'])) {
$COMPANYNAME = $_POST['COMPANYNAME'];
$COMPANYNAME = is_array($COMPANYNAME) ? $COMPANYNAME : [$COMPANYNAME];
$companiesParam = '\''. join("', '", $COMPANYNAME) . '\'';
$fetch = "SELECT sl_iv.DOCDATE, ar_iv.DUEDATE, payment_terms.terms, sl_iv.DOCNO, sl_iv.COMPANYNAME, ar_iv.DOCAMT, ar_iv.PAYMENTAMT FROM `sl_iv` Inner Join `ar_iv` On ar_iv.DOCNO = sl_iv.DOCNO Inner Join `payment_terms` On ar_iv.TERMS = payment_terms.id WHERE sl_iv.COMPANYNAME IN (".$companiesParam.") or sl_iv.DOCDATE <= '".$from."'";
$result = mysqli_query($conn_connection,$fetch)or die("MySQL error: " . mysqli_error($conn_connection) . "<hr>\nQuery: $fetch");
}