สอบถามการใช้ PHP PDO ดึงข้อมูลตามวันที่ แต่ดึงมาผิด

$stmt = $conn->prepare("SELECT TOP 500 * FROM SOHD LEFT JOIN EMCust ON EMCust.CustID=SOHD.CustID WHERE 
EmpID = $empid AND DocuStatus = 'N' AND (SOHD.DocuDate BETWEEN '$date1' AND '$date2') AND (DocuNo LIKE '%$txtKeyword%') ORDER BY SOID DESC");

$con1 = "SOHD.DocuDate BETWEEN '$date1' AND '$date2' "
   . ($txtKeyword>''? " OR SOHD.DocuNo LIKE '%$txtKeyword%'" : '');
$sql = <<<sql
SELECT TOP 500 * FROM SOHD 
LEFT JOIN EMCust ON EMCust.CustID=SOHD.CustID 
WHERE SOHD.EmpID='{$empid}' 
AND SOHD.DocuStatus = 'N' 
AND ({$con1}) 
ORDER BY DocuDate DESC
sql;

$stmt = $conn->prepare($sql);

$con1 = "SOHD.DocuDate BETWEEN :d1 AND :d2 " . ($txtKeyword>''? " OR SOHD.DocuNo LIKE :lk1 " : '');
$sql = <<<sql
SELECT TOP 500 * FROM SOHD 
LEFT JOIN EMCust ON EMCust.CustID=SOHD.CustID 
WHERE SOHD.EmpID=:id 
AND SOHD.DocuStatus = 'N' 
AND ({$con1}) 
ORDER BY DocuDate DESC
sql;

$stmt = $conn->prepare($sql);
$stmt->bindParam(':id', $empid);
$stmt->bindParam(':d1', $date1);
$stmt->bindParam(':d2', $date2);
if( $txtKeyword>''){
  $stmt->bindParam(':lk1', $txtKeyword);
}
$stmt->execute();