Summary

Synopsis

InstallShield created the MDAC Merge Module (MM) that is distributed with InstallShield for Windows Installer products (MDAC25.msm) by wrapping the Microsoft mdac_typ.exe file.

The Microsoft Data Access Components (MDAC) are the practical implementation of Microsoft's Universal Data Access strategy. MDAC 2.5 includes three distinct technologies: ODBC, OLE DB, and ADO. The MDAC MM is essentially a wrapper around Microsoft's mdac_typ.exe. It uses custom actions to check whether MDAC already exists, to execute mdac_typ.exe, and to force a reboot.

As of InstallShield 2013, InstallShield no longer has support for a number of outdated technologies. Many of these technologies have reached their end-of-life milestone and are no longer supported by Microsoft.

MDAC 2.5 is not supported in InstallShield 2013 and later.

Reference article: Removal of Outdated and Obsolete Items in InstallShield 2013

Discussion

Merge Module Dependencies: The MDAC MM specifies (in its ModuleDependency table) that it is dependent on the DCOM95 MM. InstallShield also created the DCOM95 MM.

The MM checks to see whether MDAC 2.5 is already present before running mdac_typ.exe. This check is performed as follows:

Windows 2000

If the target system is Windows 2000, MDAC 2.5 does not run mdac_typ.exe.

A clean Windows 2000 machine comes with MDAC version 2.50.4403.9, as seen in the FullInstallVer value in the registry (see next item).

Other OSs

On other OSs, the merge module checks for MDAC 2.5 by looking in the registry for the FullInstallVer value of [HKLM\Software\Microsoft\DataAccess] key. If that value exists and is greater than 2.5, the merge module does not run mdac_typ.exe. Otherwise, the merge module runs mdac_typ.exe.
Updated 10/30/00

• Improvement: Checking for the existence of MDAC 2.5 on the target machine.

• Improvement: Restarting the installation after a reboot when the installation is compressed into a single setup.exe.

• Empty directories are not created when installing MDAC 2.5.

Additional Information

Microsoft states that "as of MDAC 2.1 and later, the standalone and the re-distributable MDAC setup programs will not update files on a Windows 2000 system. With the release of Windows 2000, MDAC is part of the operating system and must be updated using operating system service packs."

InstallShield X and later users

The MDAC 2.5 Merge Module can be downloaded directly within the "Redistributables" view. Simply right-click the "Microsoft Data Access Components 2.5" Merge Module and choose "Download Selected Item...".

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