Eloquent

<?php

// Before

public function getIDsForClient()
{
    $sql = "SELECT DISTINCT FilingID FROM Snapshot1094C WHERE ClientID = ?";
    $params = [$this->clientID];
    $stmt = sqlsrv_query($this->mssqli, $sql, $params);
    $ids = [];
    while ( $row = sqlsrv_fetch_array ( $stmt, SQLSRV_FETCH_ASSOC ) ) {
        $ids[] = $row['FilingID'];
    }
    return $ids;
}

// After

public function getIDsForClient()
{
    return Snapshot1094C::where('ClientID', $this->clientID)
        ->select('FilingID')
        ->distinct('FilingID')
        ->get()
        ->pluck('FilingID')
        ->toArray();
}