5.8.2.1 Using Connector/ODBC with Microsoft Applications

The majority of Microsoft applications have been tested with Connector/ODBC, including Microsoft Office, Microsoft Access and the various programming languages supported within ASP and Microsoft Visual Studio.

5.8.2.1.1 Microsoft Access

To improve the integration between Microsoft Access and MySQL through Connector/ODBC:

• For all versions of Access, enable the Connector/ODBC Return matching rows option. For Access 2.0, also enable the Simulate ODBC 1.0 option.

• Include a TIMESTAMP column in all tables that you want to be able to update. For maximum portability, do not use a length specification in the column declaration (which is unsupported within MySQL in versions earlier than 4.1).

• Include a primary key in each MySQL table you want to use with Access. If not, new or updated rows may show up as #DELETED#.

• Use only DOUBLE float fields. Access fails when comparing with single-precision floats. The symptom usually is that new or updated rows may show up as #DELETED# or that you cannot find or update rows.

• If you are using Connector/ODBC to link to a table that has a BIGINT column, the results are displayed as #DELETED#. The work around solution is:

  • Have one more dummy column with TIMESTAMP as the data type.

  • Select the Change BIGINT columns to INT option in the connection dialog in ODBC DSN Administrator.

  • Delete the table link from Access and re-create it.

  Old records may still display as #DELETED#, but newly added/updated records are displayed properly.

• If you still get the error Another user has changed your data after adding a TIMESTAMP column, the following trick may help you:

  Do not use a table data sheet view. Instead, create a form with the fields you want, and use that form data sheet view. Set the DefaultValue property for the TIMESTAMP column to NOW(). Consider hiding the TIMESTAMP column from view so your users are not confused.

• In some cases, Access may generate SQL statements that MySQL cannot understand. You can fix this by selecting "Query|SQLSpecific|Pass-Through" from the Access menu.

• On Windows NT, Access reports BLOB columns as OLE OBJECTS. If you want to have MEMO columns instead, change BLOB columns to TEXT with ALTER TABLE.

• Access cannot always handle the MySQL DATE column properly. If you have a problem with these, change the columns to DATETIME.

• If you have in Access a column defined as BYTE, Access tries to export this as TINYINT instead of TINYINT UNSIGNED. This gives you problems if you have values larger than 127 in the column.

• If you have very large (long) tables in Access, it might take a very long time to open them. Or you might run low on virtual memory and eventually get an ODBC Query Failed error and the table cannot open. To deal with this, select the following options:

  • Return Matching Rows (2)

  • Allow BIG Results (8).

  These add up to a value of 10 (OPTION=10).

Some external articles and tips that may be useful when using Access, ODBC and Connector/ODBC:

• Read How to Trap ODBC Login Error Messages in Access

• Optimizing Access ODBC Applications

  • Optimizing for Client/Server Performance

  • Tips for Converting Applications to Using ODBCDirect

  • Tips for Optimizing Queries on Attached SQL Tables

5.8.2.1.2 Microsoft Excel and Column Types

If you have problems importing data into Microsoft Excel, particularly numeric, date, and time values, this is probably because of a bug in Excel, where the column type of the source data is used to determine the data type when that data is inserted into a cell within the worksheet. The result is that Excel incorrectly identifies the content and this affects both the display format and the data when it is used within calculations.

To address this issue, use the CONCAT() function in your queries. The use of CONCAT() forces Excel to treat the value as a string, which Excel will then parse and usually correctly identify the embedded information.

However, even with this option, some data may be incorrectly formatted, even though the source data remains unchanged. Use the Format Cells option within Excel to change the format of the displayed information.

5.8.2.1.3 Microsoft Visual Basic

To be able to update a table, you must define a primary key for the table.

Visual Basic with ADO cannot handle big integers. This means that some queries like SHOW PROCESSLIST do not work properly. The fix is to use OPTION=16384 in the ODBC connect string or to select the Change BIGINT columns to INT option in the Connector/ODBC connect screen. You may also want to select the Return matching rows option.

5.8.2.1.4 Microsoft Visual InterDev

If you have a BIGINT in your result, you may get the error [Microsoft][ODBC Driver Manager] Driver does not support this parameter. Try selecting the Change BIGINT columns to INT option in the Connector/ODBC connect screen.

5.8.2.1.5 Visual Objects

Select the Don't optimize column widths option.

5.8.2.1.6 Microsoft ADO

When you are coding with the ADO API and Connector/ODBC, you need to pay attention to some default properties that aren't supported by the MySQL server. For example, using the CursorLocation Property as adUseServer returns a result of −1 for the RecordCount Property. To have the right value, you need to set this property to adUseClient, as shown in the VB code here:

Dim myconn As New ADODB.Connection
Dim myrs As New Recordset
Dim mySQL As String
Dim myrows As Long
myconn.Open "DSN=MyODBCsample"
mySQL = "SELECT * from user"
myrs.Source = mySQL
Set myrs.ActiveConnection = myconn
myrs.CursorLocation = adUseClient
myrs.Open
myrows = myrs.RecordCount
myrs.Close
myconn.Close

Another workaround is to use a SELECT COUNT(*) statement for a similar query to get the correct row count.

To find the number of rows affected by a specific SQL statement in ADO, use the RecordsAffected property in the ADO execute method. For more information on the usage of execute method, refer to http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ado270/htm/mdmthcnnexecute.asp.

For information, see ActiveX Data Objects(ADO) Frequently Asked Questions.

5.8.2.1.7 Using Connector/ODBC with Active Server Pages (ASP)

Select the Return matching rows option in the DSN.

For more information about how to access MySQL through ASP using Connector/ODBC, refer to the following articles:

• Using MyODBC To Access Your MySQL Database Via ASP

• ASP and MySQL at DWAM.NT

A Frequently Asked Questions list for ASP can be found at http://support.microsoft.com/default.aspx?scid=/Support/ActiveServer/faq/data/adofaq.asp.

5.8.2.1.8 Using Connector/ODBC with Visual Basic (ADO, DAO and RDO) and ASP

Some articles that may help with Visual Basic and ASP:

• MySQL BLOB columns and Visual Basic 6 by Mike Hillyer (<[e-mail]>).

• How to map Visual basic data type to MySQL types by Mike Hillyer (<[e-mail]>).