22.1.7.2. Connector/ODBC Application Specific Tips

Most programs should work with Connector/ODBC, but for each of those listed here, there are specific notes and tips to improve or enhance the way you work with Connector/ODBC and these applications.

With all applications you should ensure that you are using the latest Connector/ODBC drivers, ODBC Manager and any supporting libraries and interfaces used by your application. For example, on Windows, using the latest version of Microsoft Data Access Components (MDAC) will improve the compatibility with ODBC in general, and with the Connector/ODBC driver.

22.1.7.2.1. 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.

22.1.7.2.1.1. Microsoft Access

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

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

  • You should have 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).

  • You should have 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. You should set the DefaultValue property for the TIMESTAMP column to NOW(). It may be a good idea to hide 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, you should 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:

22.1.7.2.1.2. 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.

22.1.7.2.1.3. 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.

22.1.7.2.1.4. 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.

22.1.7.2.1.5. Visual Objects

You should select the Don't optimize column widths option.

22.1.7.2.1.6. 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.

22.1.7.2.1.7. Using Connector/ODBC with Active Server Pages (ASP)

You should 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:

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

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

Some articles that may help with Visual Basic and ASP:

22.1.7.2.2. Using Connector/ODBC with Borland Applications

With all Borland applications where the Borland Database Engine (BDE) is used, follow these steps to improve compatibility:

  • Update to BDE 3.2 or newer.

  • Enable the Don't optimize column widths option in the DSN.

  • Enabled the Return matching rows option in the DSN.

22.1.7.2.2.1. Using Connector/ODBC with Borland Builder 4

When you start a query, you can use the Active property or the Open method. Note that Active starts by automatically issuing a SELECT * FROM ... query. That may not be a good thing if your tables are large.

22.1.7.2.2.2. Using Connector/ODBC with Delphi

Also, here is some potentially useful Delphi code that sets up both an ODBC entry and a BDE entry for Connector/ODBC. The BDE entry requires a BDE Alias Editor that is free at a Delphi Super Page near you. (Thanks to Bryan Brunton for this):

fReg:= TRegistry.Create;
fReg.OpenKey('\Software\ODBC\ODBC.INI\DocumentsFab', True);
fReg.WriteString('Database', 'Documents');
fReg.WriteString('Description', ' ');
fReg.WriteString('Driver', 'C:\WINNT\System32\myodbc.dll');
fReg.WriteString('Flag', '1');
fReg.WriteString('Password', '');
fReg.WriteString('Port', ' ');
fReg.WriteString('Server', 'xmark');
fReg.WriteString('User', 'winuser');
fReg.OpenKey('\Software\ODBC\ODBC.INI\ODBC Data Sources', True);
fReg.WriteString('DocumentsFab', 'MySQL');
fReg.CloseKey;
fReg.Free;

Memo1.Lines.Add('DATABASE NAME=');
Memo1.Lines.Add('USER NAME=');
Memo1.Lines.Add('ODBC DSN=DocumentsFab');
Memo1.Lines.Add('OPEN MODE=READ/WRITE');
Memo1.Lines.Add('BATCH COUNT=200');
Memo1.Lines.Add('LANGDRIVER=');
Memo1.Lines.Add('MAX ROWS=-1');
Memo1.Lines.Add('SCHEMA CACHE DIR=');
Memo1.Lines.Add('SCHEMA CACHE SIZE=8');
Memo1.Lines.Add('SCHEMA CACHE TIME=-1');
Memo1.Lines.Add('SQLPASSTHRU MODE=SHARED AUTOCOMMIT');
Memo1.Lines.Add('SQLQRYMODE=');
Memo1.Lines.Add('ENABLE SCHEMA CACHE=FALSE');
Memo1.Lines.Add('ENABLE BCD=FALSE');
Memo1.Lines.Add('ROWSET SIZE=20');
Memo1.Lines.Add('BLOBS TO CACHE=64');
Memo1.Lines.Add('BLOB SIZE=32');

AliasEditor.Add('DocumentsFab','MySQL',Memo1.Lines);
22.1.7.2.2.3. Using Connector/ODBC with C++ Builder

Tested with BDE 3.0. The only known problem is that when the table schema changes, query fields are not updated. BDE, however, does not seem to recognize primary keys, only the index named PRIMARY, although this has not been a problem.

22.1.7.2.3. Using Connector/ODBC with ColdFusion

The following information is taken from the ColdFusion documentation:

Use the following information to configure ColdFusion Server for Linux to use the unixODBC driver with Connector/ODBC for MySQL data sources. You can download Connector/ODBC at http://dev.mysql.com/downloads/connector/odbc/.

ColdFusion version 4.5.1 enables you to use the ColdFusion Administrator to add the MySQL data source. However, the driver is not included with ColdFusion version 4.5.1. Before the MySQL driver appears in the ODBC data sources drop-down list, you must build and copy the Connector/ODBC driver to /opt/coldfusion/lib/libmyodbc.so.

The Contrib directory contains the program mydsn-xxx.zip which enables you to build and remove the DSN registry file for the Connector/ODBC driver on ColdFusion applications.

For more information and guides on using ColdFusion and Connector/ODBC, see the following external sites:

22.1.7.2.4. Using Connector/ODBC with OpenOffice.org

Open Office (http://www.openoffice.org) How-to: MySQL + OpenOffice. How-to: OpenOffice + MyODBC + unixODBC.

22.1.7.2.5. Using Connector/ODBC with Sambar Server

Sambar Server (http://www.sambarserver.info) How-to: MyODBC + SambarServer + MySQL.

22.1.7.2.6. Using Connector/ODBC with Pervasive Software DataJunction

You have to change it to output VARCHAR rather than ENUM, as it exports the latter in a manner that causes MySQL problems.

22.1.7.2.7. Using Connector/ODBC with SunSystems Vision

You should select the Return matching rows option.

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