ขอคำสั่งกรอกจำนวนตัวเลขไม่เกินที่เรากำหนดหน่อยคับ

<form name="register" method="post" action="insert_register.php">
<table width="500" height="250" border="1">
  <tr>
    <td width="137"><font size="4">เลขบัตรประชาชน</font></td>
    <td width="347"><input type="text" name="txtName_id" id="txtName_id" size="50" /></td>
  </tr>
  <tr>
    <td><font size="4">ชื่อ-สกุล</font></td>
    <td><input type="text" name="txtName" id="txtName" size="50" /></td>
  </tr>
  <tr>
    <td><font size="4">ที่อยู่</font></td>
    <td>
    <textarea name="txtAddress" id="txtAddress" rows="5" cols="55"></textarea>
    </td>
  </tr>
  <tr>
    <td><font size="4">User</font></td>
    <td><input type="text" name="txtUser" id="txtUser" size="50" /></td>
  </tr>
  <tr>
    <td><font size="4">Password</font></td>
    <td><input type="text" name="txtPwd" id="txtPwd" size="50" /></td>
  </tr>
  <tr>
    <td><font size="4">E-mail</font></td>
    <td><input type="text" name="txtEmail" id="txtEmail" size="50" /></td>
  </tr>
  <tr>
    <td><font size="4">โทรศัพท์</font></td>
    <td><input type="text" name="txtTel" id="txtTel" size="50" /></td>
  </tr>
  
</table><br />
	<input type="submit" name="Submit" value="สมัครสมาชิก">
 	<input type="reset" name="Reset" value="ยกเลิก">

</form>

<?php
ob_start();
	
?>


<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<?
include ('config.inc.php');
	if(trim($_POST["txtName_id"]) == "")
	{
		echo "<script language=\"JavaScript\" type=\"text/JavaScript\">alert('คุณไม่ได้กรอกเลขบัตรประชาชน') </script> ";
		echo"<meta http-equiv='refresh' content='0;url=index.php?id=7'>";
		exit();	
	}
	if(trim($_POST["txtName"]) == "")
	{
		echo "<script language=\"JavaScript\" type=\"text/JavaScript\">alert('คุณไม่ได้กรอกชื่อ') </script> ";
		echo"<meta http-equiv='refresh' content='0;url=index.php?id=7'>";
		exit();	
	}
	if(trim($_POST["txtAddress"]) == "")
	{
		echo "<script language=\"JavaScript\" type=\"text/JavaScript\">alert('คุณไม่ได้กรอกที่อยู่') </script> ";
		echo"<meta http-equiv='refresh' content='0;url=index.php?id=7'>";
		exit();	
	}
	if(trim($_POST["txtUser"]) == "")
	{
		echo "<script language=\"JavaScript\" type=\"text/JavaScript\">alert('คุณไม่ได้กรอก USER') </script> ";
		echo"<meta http-equiv='refresh' content='0;url=index.php?id=7'>";
		exit();	
	}
	
	
	if(trim($_POST["txtPwd"]) == "")
	{
		
		echo "<script language=\"JavaScript\" type=\"text/JavaScript\">alert('คุณไม่ได้กรอกรหัสผ่าน') </script> ";
		echo"<meta http-equiv='refresh' content='0;url=index.php?id=7'>";
		exit();
	}	
		
		if(trim($_POST["txtEmail"]) == "")
	{
		
		echo "<script language=\"JavaScript\" type=\"text/JavaScript\">alert('คุณไม่ได้กรอกอีเมล์คับ') </script> ";
		echo"<meta http-equiv='refresh' content='0;url=index.php?id=7'>";
		exit();
	}	
	
	if(trim($_POST["txtTel"]) == "")
	{
		
		echo "<script language=\"JavaScript\" type=\"text/JavaScript\">alert('คุณไม่ได้กรอก่เบอร์โทรศัพท์') </script> ";
		echo"<meta http-equiv='refresh' content='0;url=index.php?id=7'>";
		exit();
	}	
	
	
	else
	{	
	}
$strSQL = "INSERT INTO register ";
$strSQL .="(Name_id,Name1,Address,User,Pwd,E_mail,Tel) ";
$strSQL .="VALUES ";
	$strSQL .="('".$_POST["txtName_id"]."','".$_POST["txtName"]."' ";
	$strSQL .=",'".$_POST["txtAddress"]."','".$_POST["txtUser"]."' ";
	$strSQL .=",'".$_POST["txtPwd"]."','".$_POST["txtEmail"]."' ";
	$strSQL .=",'".$_POST["txtTel"]."') ";
$objQuery = mysql_query($strSQL);
if($objQuery)
{
	echo "<script language='javascript'>alert('complete');history.back();window.location='index.php?id=1';</script>";
	
	
}
else
{
	echo "Error Save [".$strSQL."]";
}
mysql_close();
?>