FIX: "Syntax Error" with SQL Literal String Over 16,379 Bytes (194127)

SYMPTOMS

If you attempt to execute a SQL INSERT statement that contains a literal string having over 16,379 characters with the Microsoft ODBC Driver for Access, the following error message occurs:

[Microsoft][ODBC Microsoft Access 97 Driver]
Syntax error in INSERT INTO statement.

SQL UPDATE SQL statements with literal strings over 16,379 bytes also fail with a similar error.

CAUSE

The SQL parser for the Microsoft ODBC Driver for Access prior to 4.0.4202 does not accept string literals larger than 16,379 bytes. This is the defined limit for literal strings in a SQL statement for the Microsoft ODBC Driver for Access.

With the Microsoft ODBC Driver for Access versions 4.0.4202 and later, you can execute a SQL INSERT containing a string literal having over 16,379 characters. However, you will get the following error message with a SQL INSERT that contains a literal string having over 516,076 characters:

[Microsoft][ODBC Microsoft Access Driver]
Query is too complex

This error occurs with both Access 97 and Access 2000 databases.

RESOLUTION

There are two possible workarounds for the syntax error:

The Microsoft ODBC Driver for Access versions 4.0.4202 and later allow SQL INSERTS with string literals having up to 516,076 characters.
Use parameterized insert or updates rather than embedding literal strings into the SQL statements if you expect to insert or update large string values. This resolution works with all versions of the Microsoft ODBC Driver for Access.

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

This bug has been fixed in the Microsoft ODBC Driver for Access versions 4.0.4202 and later. Note that version 4.0.4202 of the Odbcjt32.dll file is installed by MDAC 2.1 service pack 2.

However, a new limitation of 516,076 characters now applies.

You may obtain the latest version of the Microsoft Data Access Components from the following Microsoft Web site:

http://msdn.microsoft.com/library/default.asp?url=/downloads/list/dataaccess.asp

MORE INFORMATION

Steps to Reproduce Behavior

Run the following sample code to reproduce the problem and demonstrate the workaround. Note that the sample requires a blank Microsoft Access database named c:\db1.mdb and a reference to the Microsoft ActiveX Data Objects Library.

If testing the Microsoft ODBC Driver for Access version 4.0.4202 or later, use the following numbers to test:

In place of 16379, use 516076
In place of 16380, use 516077

Sample Code

   ' START SAMPLE CODE
   Sub TestMemo()
   Dim conn As New ADODB.Connection
   Dim cmd As New ADODB.Command
   Dim strSQL As String

      conn.Open "Driver={Microsoft Access Driver (*.mdb)};" & _
                "DBQ=c:\db1.mdb"
      On Error Resume Next
      conn.Execute "DROP TABLE tmp_MEMO1234"
      On Error GoTo 0
      conn.Execute "create table tmp_MEMO1234 (data1 memo)"

      ' Using a parameterized insert works.
      cmd.ActiveConnection = conn
      cmd.CommandText = "insert into tmp_MEMO1234 (data1) values (?)"
      cmd.CommandType = adCmdText
      cmd.Parameters.Append cmd.CreateParameter("p1", _
                            adLongVarChar, adParamInput, -1)
      cmd.Parameters(0).Value = String(16380, "X")
      cmd.Execute ' SUCCESS

      ' Literal string 16379 bytes or less works.
      strSQL = "insert into tmp_MEMO1234 (data1) values ('" & _
               String(16379, "X") & "')"
      conn.Execute strSQL ' SUCCESS

      ' Literal string 16380 bytes or larger fails.
      strSQL = "insert into tmp_MEMO1234 (data1) values ('" & _
               String(16380, "X") & "')"
      conn.Execute strSQL ' FAILS HERE

   End Sub
   ' END SAMPLE CODE