Encoding Form Data for SQL Server Input and Output to HTML

ID: Q246069

The information in this article applies to:

Microsoft Internet Information Services version 5.0

SUMMARY

When you are working with records in a database using Microsoft Active Server Pages (ASP) for Internet Information Services (IIS), errors may occur when the text has not been properly formatted for creating a SQL Server clause.

For example, when you create an ASP page to store information posted from an HTML form to a database, you may see an error message similar to the following:

Microsoft OLE DB Provider for ODBC Drivers (0x80040E14)
[Microsoft][ODBC Microsoft Access Driver] Syntax error (missing operator) in query expression '<SQL Text>'.
/<path>/<filename.asp>, line <nnn>

MORE INFORMATION

The error message above occurs when you try to submit a name with an apostrophe, (for example "O'Malley"), and then insert that name into a SQL Server clause without first "escaping" it. This can result in a SQL Server clause that resembles the following:


INSERT INTO Table (txtName VALUES ('O'Malley')

Because SQL Server uses the apostrophe as a text delimiter, the apostrophe in the name inadvertently signifies an end to the data, which causes the error message to occur. This text can be "escaped" by using two apostrophes, for example:


INSERT INTO Table (txtName VALUES ('O''Malley')

Obviously, it is not ideal to mandate that all users on a Web site enter two apostrophes for each desired apostrophe. In addition, when text is later extracted from a database, certain formatting characters are ignored during HTML parsing on a client (for example CR-LF, TAB, and so on.)

An ASP Solution

The following ASP code defines two functions that are designed to handle some simple parsing of information for input/output of SQL Server data, and can easily be expanded to incorporate more functionality:

FixForSQL() parses a string for input to SQL Server


  Function FixForSQL(tmpText1)
    ' define a working variable
    Dim tmpText2
    ' populate our working variable
    tmpText2 = tmpText1
    ' compact a CR-LF sequence as CR to save space
    tmpText2 = Replace(tmpText1,vbCrLf,Chr(13))
    ' replace each apostrophe with two apostrophes
    tmpText2 = Replace(tmpText2,Chr(39),String(2,39))
    ' return the fixed string
    FixForSQL = tmpText2
  End Function

FixForHTML() parses a string for output to HTML


  Function FixForHTML(tmpText1)
    ' define a working variable
    Dim tmpText2
    ' populate our working variable
    tmpText2 = tmpText1
    ' replace each CR with a line break tag and CR-LF
    tmpText2 = Replace(tmpText2,Chr(13),"<br>" & vbCrLf)
    ' replace each TAB character with four non-breaking space tags
    tmpText2 = Replace(tmpText2,Chr(9),"&#xa0;&#xa0;&#xa0;&#xa0;")
    ' return the fixed string
    FixForHTML = tmpText2
  End Function

Practical Example - Guestbook Application

The following steps demonstrate how to use the above functions to create a simple guestbook application using ASP and a Microsoft Access database:

Copy the following ASP code and save it to a folder in your Web site with at least IIS script access enabled and Copy the following ASP code and save it to a folder in your Web site with at least IIS "script" access enabled and Everyone - Change NTFS permissions:


<% @Language="VBScript" %>
<%
  Option Explicit

  ' define our variables
  Dim strMethod
  Dim strURL
  Dim strTitle
  Dim strSQL
  Dim objCN
  Dim objRS

  ' get some environment variables
  With Request
    strMethod = UCase(.ServerVariables("REQUEST_METHOD"))
    strTitle = UCase(.ServerVariables("SERVER_NAME")) & " Guestbook"
    strURL = LCase(.ServerVariables("URL"))
  End With

  ' open our database connection
  Set objCN = Server.CreateObject("ADODB.Connection")
  objCN.Open "driver={Microsoft Access Driver (*.mdb)};uid=admin;pwd=;" & _
    "dbq=" & Server.MapPath(".\guestbook.mdb")

  ' if the request was a POST then a guest submitted
  If strMethod = "POST" Then
    Dim strName, strComments
    ' get the form data and format it
    strName = FixForSQL(Request.Form("txtName"))
    strComments = FixForSQL(Request.Form("txtComments"))
    ' build the SQL string
    strSQL = "INSERT INTO tblGuestbook (txtName, txtComments)"
    strSQL = strSQL & " VALUES ('" & strName & "','" & strComments & "')"
    ' execute the SQL
    objCN.Execute(strSQL)
  End If

  ' create a SQL string to read all guest entries
  strSQL = "SELECT * FROM tblGuestbook"
  Set objRS = objCN.Execute(strSQL)

%>
<html>
<head><title><%=strTitle%></title></head>
<body>

<h1><%=strTitle%></h1>

<%
  ' only show the guestbook when there are entries
  If Not objRS.EOF Then
%>

<table border="1">
  <tr>
    <th>Name</th>
    <th>Comments</th>
  </tr>
<%
  ' loop through the database
  While Not objRS.EOF
    With Response
      .Write "<tr>" & vbCrLf
      .Write "<td>" & FixForHTML(objRS("txtName")) & "</td>" & vbCrLf
      .Write "<td>" & FixForHTML(objRS("txtComments")) & "</td>" & vbCrLf
      .Write "</tr>" & vbCrLf
    End With
    objRS.MoveNext
  Wend
%>
</table>

<% End If %>

<form action="<%=strURL%>" method="POST">
  <table>
    <tr>
      <td>Name</td>
      <td><input type="text" name="txtName"><br>
    </tr>
    <tr>
      <td>Comments</td>
      <td><textarea name="txtComments"></textarea><br>
    </tr>
    <tr>
      <td colspan="2"><input type="submit" value="Submit Comments">
    </tr>
</form>

</body>
</html>
<%
  Function FixForSQL(tmpText1)
    Dim tmpText2
    tmpText2 = tmpText1
    tmpText2 = Replace(tmpText1,vbCrLf,Chr(13))
    tmpText2 = Replace(tmpText2,Chr(39),String(2,39))
    FixForSQL = tmpText2
  End Function

  Function FixForHTML(tmpText1)
    Dim tmpText2
    tmpText2 = tmpText1
    tmpText2 = Replace(tmpText2,Chr(13),"<br>" & vbCrLf)
    tmpText2 = Replace(tmpText2,Chr(9),"&#xa0;&#xa0;&#xa0;&#xa0;")
    FixForHTML = tmpText2
  End Function
%>

Open Microsoft Access, create a new database, and then save it as Guestbook.mdb in the same folder as the above ASP page.
Create a new table in the database named TblGuestbook with the following fields:
Field Name Data Type Field Size

txtName Text 50

txtComments Text 255
Save the table to the database, and then close Microsoft Access.

Testing the Guestbook Application

When you browse the page for the first time, no data is displayed.
When information has been submitted, any guestbook entries will appear.
Entering apostrophes in names (for example O'Brien, O'Sullivan, and so on) or contractions (such as don't, can't, and so on) are properly formatted and stored in the database.

REFERENCES

Microsoft provides programming examples for illustration only, without warranty either expressed or implied, including, but not limited to, the implied warranties of merchantability and/or fitness for a particular purpose. This article assumes that you are familiar with the programming language being demonstrated and the tools used to create and debug procedures. Microsoft support professionals can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific needs. If you have limited programming experience, you may want to contact a Microsoft Certified Solution Provider or the Microsoft fee-based consulting line at (800) 936-5200. For more information about Microsoft Certified Solution Providers, please see the following page on the World Wide Web:

http://www.microsoft.com/mcsp/

For more information about the support options available from Microsoft, please see the following page on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

For more information on Microsoft scripting technologies, see the Microsoft Developer Network web site at the following URL:

http://msdn.microsoft.com/scripting/

Additional query words: iis

Keywords :
Version : winnt:5.0
Platform : winnt
Issue type : kbinfo