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Development: ODBC Interface

ODBC Datasources

The standard ODBC interface uses datasources to connect to an underlying database. Datasources provide the connection information to get to the underlying data, and each database vendor must provide their own interface to creating these datasources. Omnidex provides several options for datasources.

The Omnidex ODBC Driver supports the standard methods of connecting to the databases - Machine Datasources (SYSTEM and USER Datasources) and File Datasources. The driver supports DSN-less connections as well.

Machine Datasources

The standard ODBC interface provides the ability to create two types of Machine Datasources: System Datasources and User Datasources. When creating one of these datasources, the ODBC Data Source Administrator provided by Microsoft will automatically launch an Omnidex wizard to prompt you through the creation process. Consult this tutorial for instructions about creating datasources using this wizard.

Once the Machine Datasource has been created, it can be referenced by name in third-party applications that use ODBC. Consult each third-party applications' documentation for instructions about referencing Machine Datasources in their application.

Machine Datasources can also be referenced in an ODBC call to either SQLConnect or SQLDriverConnect. In the following example, the name of the Machine Datasource is simple.

SQLConnect( hdbc, 
            (SQLCHAR*) "simple",  
            SQL_NTS, NULL, 0, NULL, 0);
SQLDriverConnect( hdbc, NULL, 
                  (SQLCHAR*) "DSN=simple", 
                  SQL_NTS, NULL, 0, NULL, SQL_DRIVER_NOPROMPT); 

File Datasources

The standard ODBC interface provides the ability to create File Datasources. Microsoft's ODBC Data Source Administrator will automatically launch an Omnidex wizard to prompt you through the creation process for File Datasources as well. Consult this tutorial for instructions about creating datasources using this wizard.

It is also possible to manually create File Datasources for Linux computers that run a Linux-based ODBC Manager, such as unixODBC. These can be created using a text editor. Consult the ODBC File DSN Syntax Specification for instruction on manually creating these files.

Once the File Datasource has been created, it can be referenced in third-party applications using the filename. Consult each third-party applications' documentation for instructions about referencing File Datasources in their application.

File Datasources can also be referenced in a call to SQLDriverConnect.

SQLDriverConnect( hdbc, NULL, 
                  (SQLCHAR*) "FILEDSN=simple.dsn", 
                  SQL_NTS, NULL, 0, NULL, SQL_DRIVER_NOPROMPT);

DSN-Less Connection

Omnidex also allows ODBC applications to connect to an Environment File without the need for a Machine or File Datasource. All of the needed information is found in the connection string. This approach may not be supported by some third-party applications; however, it can always be used in custom applications that call SQLDriverConnect.

SQLDriverConnect( hdbc, NULL, 
                  (SQLCHAR*) "DRIVER={OMNIDEX}; 
                              CONNECTIONSTRING=[dbserver:7555]D:\\class\\simple.xml", 
                  SQL_NTS, NULL, 0, NULL, SQL_DRIVER_NOPROMPT);

Additional Resources

See also:

 
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dev/odbc/datasources.1294866467.txt.gz ยท Last modified: 2016/06/28 22:38 (external edit)