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6.5 SQLRemoveDriver

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The following specification of SQLRemoveDriver is from the Microsoft ODBC SDK Reference.

Summary

SQLRemoveDriver changes or removes information about the driver from the ODBCINST.INI entry in the system information.

Syntax

BOOL SQLRemoveDriver ( 
LPCSTR lpszDriver, 
BOOL fRemoveDSN, 
LPDWORD lpdwUsageCount); 

Arguments

lpszDriver [Input]

The name of the driver as registered in the ODBCINST.INI key of the system information.

fRemoveDSN [Input]

The valid values are:

• TRUE:

Remove DSNs associated with the driver specified in lpszDriver.

• FALSE:

Do not remove DSNs associated with the driver specified in lpszDriver.

lpdwUsageCount [Output]

The usage count of the driver after this function has been called.

Returns

The function returns TRUE if it is successful, FALSE if it fails. If no entry exists in the system information when this function is called, the function returns FALSE.

Diagnostics

When SQLRemoveDriver returns FALSE, an associated *pfErrorCode value may be obtained by calling SQLInstallerError.

The following table lists the *pfErrorCode values that can be returned by SQLInstallerError and explains each one in the context of this function.

*pfErrorCode	Error	Description
ODBC_ERROR_ GENERAL_ERR	General installer error	An error occurred for which there was no specific installer error.
ODBC_ERROR_ COMPONENT_ NOT_FOUND	Component not found in registry	The installer could not remove the driver information because it either did not exist in the registry or could not be found in the registry.
ODBC_ERROR_ INVALID_NAME	Invalid driver or translator name	The lpszDriver argument was invalid.
ODBC_ERROR_ USAGE_UPDATE_ FAILED	Could not increment or decrement the component usage count	The installer failed to decrement the usage count of the driver.
ODBC_ERROR_ REQUEST_FAILED	Request failed	The fRemoveDSN argument was TRUE; however, one or more DSNs could not be removed. The call to SQLConfigDriver with the ODBC_REMOVE_DRIVER request failed.
ODBC_ERROR_ OUT_OF_MEM	Out of memory	The installer could not perform the function because of a lack of memory.

Comments

SQLRemoveDriver complements the SQLInstallDriverEx function, and updates the component usage count in the system information. This function should only be called from a setup application.

SQLRemoveDriver will decrement the component usage count value by 1. If the component usage count goes to 0 then the following will occur:

• The SQLConfigDriver function with the ODBC_REMOVE_DRIVER option will be called. If the fRemoveDSN option is set to TRUE, the ConfigDSN function calls SQLRemoveDSNFromIni to remove all the data sources associated with the driver specified in lpszDriver. If the fRemoveDSN option is set to FALSE, the data sources will not be deleted.
• The driver entry in the system information will be removed. The driver entry is in the following system information location, under the driver name:

HKEY_LOCAL_MACHINE 

SOFTWARE

ODBC

ODBCINST.INI

SQLRemoveDriver does not actually remove any files. The calling program is responsible for deleting files, and maintaining the file usage count. Only after both the component usage count and the file usage count have reached zero is a file physically deleted. Some files in a component can be deleted, and others not deleted, depending upon whether the files are used by other applications that have incremented the file usage count.

SQLRemoveDriver is also called as part of an upgrade process. If an application detects that it has to perform an upgrade, and it has previously installed the driver, then the driver should be removed, then reinstalled.

SQLRemoveDriver should first be called to decrement the component usage count, then SQLInstallDriverEx should then be called to increment the component usage count. The application setup program must physically replace the old files with the new files.

The file usage count will remain the same, and other applications that use the older version files will now use the newer version.

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