MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 22: Setup DLL API Reference

ConfigDSN

Conformance

Version Introduced: ODBC 1.0

Summary

ConfigDSN adds, modifies, or deletes data sources from the system information. It may prompt the user for connection information. It can be in the driver DLL or a separate setup DLL.

Syntax

BOOL ConfigDSN(
     HWND     hwndParent,
     WORD     fRequest,
     LPCSTR     lpszDriver,
     LPCSTR     lpszAttributes);

Arguments

hwndParent

[Input]
Parent window handle. The function will not display any dialog boxes if the handle is null.

fRequest

[Input]
Type of request. The fRequest argument must contain one of the following values:

ODBC_ADD_DSN: Add a new data source.
ODBC_CONFIG_DSN: Configure (modify) an existing data source.
ODBC_REMOVE_DSN: Remove an existing data source.

lpszDriver

[Input]
Driver description (usually the name of the associated DBMS) presented to users instead of the physical driver name.

lpszAttributes

[Input]
List of attributes in the form of keyword-value pairs. For information about the list structure, see "Comments."

Returns

The function returns TRUE if it is successful, FALSE if it fails.

Diagnostics

When ConfigDSN returns FALSE, an associated *pfErrorCode value is posted to the installer error buffer by a call to SQLPostInstallerError and can 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.

Comments

ConfigDSN receives connection information from the installer DLL as a list of attributes in the form of keyword-value pairs. Each pair is terminated with a null byte, and the entire list is terminated with a null byte. (That is, two null bytes mark the end of the list.) Spaces are not allowed around the equal sign in the keyword-value pair. ConfigDSN can accept keywords that are not valid keywords for SQLBrowseConnect and SQLDriverConnect. ConfigDSN does not necessarily support all keywords that are valid keywords for SQLBrowseConnect and SQLDriverConnect. (ConfigDSN does not accept the DRIVER keyword.) The keywords used by the ConfigDSN function must support all the options required to re-create the data source using the AUTO setup feature of the installer. When the uses of the ConfigDSN values and the connection string values are the same, the same keywords should be used.

As in SQLBrowseConnect and SQLDriverConnect, the keywords and their values should not contain the []{}(),;?*=!@ characters, and the value of the DSN keyword cannot consist only of blanks. Because of the registry grammar, keywords and data source names cannot contain the backslash (\) character.

ConfigDSN should call SQLValidDSN to check the length of the data source name and to verify that no invalid characters are included in the name. If the data source name is longer than SQL_MAX_DSN_LENGTH or includes invalid characters, SQLValidDSN returns an error and ConfigDSN returns an error. The length of the data source name is also checked by SQLWriteDSNToIni.

For example, to configure a data source that requires a user ID, password, and database name, a setup application might pass the following keyword-value pairs:

DSN=Personnel Data\0UID=Smith\0PWD=Sesame\0DATABASE=Personnel\0\0

For more information about these keywords, see SQLDriverConnect and each driver's documentation.

To display a dialog box, hwndParent must not be null.

Adding a Data Source

If a data source name is passed to ConfigDSN in lpszAttributes, ConfigDSN checks that the name is valid. If the data source name matches an existing data source name and hwndParent is null, ConfigDSN overwrites the existing name. If it matches an existing name and hwndParent is not null, ConfigDSN prompts the user to overwrite the existing name.

If lpszAttributes contains enough information to connect to a data source, ConfigDSN can add the data source or display a dialog box with which the user can change the connection information. If lpszAttributes does not contain enough information to connect to a data source, ConfigDSN must determine the necessary information; if hwndParent is not null, it displays a dialog box to retrieve the information from the user.

If ConfigDSN displays a dialog box, it must display any connection information passed to it in lpszAttributes. In particular, if a data source name was passed to it, ConfigDSN displays that name but does not allow the user to change it. ConfigDSN can supply default values for connection information not passed to it in lpszAttributes.

If ConfigDSN cannot get complete connection information for a data source, it returns FALSE.

If ConfigDSN can get complete connection information for a data source, it calls SQLWriteDSNToIni in the installer DLL to add the new data source specification to the Odbc.ini file (or registry). SQLWriteDSNToIni adds the data source name to the [ODBC Data Sources] section, creates the data source specification section, and adds the DRIVER keyword with the driver description as its value. ConfigDSN calls SQLWritePrivateProfileString in the installer DLL to add any additional keywords and values used by the driver.

Modifying a Data Source

To modify a data source, a data source name must be passed to ConfigDSN in lpszAttributes. ConfigDSN checks that the data source name is in the Odbc.ini file (or registry).

If hwndParent is null, ConfigDSN uses the information in lpszAttributes to modify the information in the Odbc.ini file (or registry). If hwndParent is not null, ConfigDSN displays a dialog box using the information in lpszAttributes; for information not in lpszAttributes, it uses information from the system information. The user can modify the information before ConfigDSN stores it in the system information.

If the data source name was changed, ConfigDSN first calls SQLRemoveDSNFromIni in the installer DLL to remove the existing data source specification from the Odbc.ini file (or registry). It then follows the steps in the preceding section to add the new data source specification. If the data source name was not changed, ConfigDSN calls SQLWritePrivateProfileString in the installer DLL to make any other changes. ConfigDSN may not delete or change the value of the Driver keyword.

Deleting a Data Source

To delete a data source, a data source name must be passed to ConfigDSN in lpszAttributes. ConfigDSN checks that the data source name is in the Odbc.ini file (or registry). It then calls SQLRemoveDSNFromIni in the installer DLL to remove the data source.

Related Functions