Microsoft Data Access Components (MDAC; also known as Windows DAC) is a framework of interrelated Microsoft technologies that allows programmers a uniform and comprehensive way of developing applications that can access almost any data store. Its components include: ActiveX Data Objects (ADO), OLE DB, and Open Database Connectivity (ODBC). There have been several deprecated components as well, such as the Jet Database Engine, MSDASQL (the OLE DB provider for ODBC), and Remote Data Services (RDS). Some components have also become obsolete, such as the former Data Access Objects API and Remote Data Objects.
Microsoft Data Access Components Mdac Version 2.6 Download
The latest version of MDAC (2.8) consists of several interacting components, all of which are Windows specific except for ODBC (which is available on several platforms). MDAC architecture may be viewed as three layers: a programming interface layer, consisting of ADO and ADO.NET, a database access layer developed by database vendors such as Oracle and Microsoft (OLE DB, .NET managed providers and ODBC drivers), and the database itself. These component layers are all made available to applications through the MDAC API. The Microsoft SQL Server Network Library, a proprietary access method specific to Microsoft SQL Server, is also included in the MDAC. Developers of Windows applications are encouraged to use ADO or ADO.NET for data access, the benefit being that users of the application program are not constrained in their choice of database architecture except that it should be supported by MDAC. Naturally, developers still have the choice of writing applications which directly access OLE DB and ODBC.
Jet stands for Joint Engine Technology and was a database engine used for Microsoft Access, Microsoft Exchange Server and Visual Basic. Jet was part of a Relational Database Management System (RDBMS) and offered a single interface that other software could use to access Microsoft databases. Jet also provided support for security, referential integrity, transaction processing, indexing, record and page locking, and data replication. In later versions of Jet, the engine was extended to run SQL queries, store character data in Unicode format, create views, and allowed bi-directional replication with the Microsoft SQL Server. It was superseded by MSDE which was superseded SQL Server Express.
SQLXML was designed for SQL Server 2000, but was deprecated with MDAC 2.6. It allowed Microsoft's relational database to be viewed by XPath and allowed data to viewable as an XML file. It has not actually been deprecated but has been removed from later versions of MDAC, though Microsoft does provide it as a downloadable component and will support it on their 64-bit operating systems.
This version of MDAC had a security flaw that made it vulnerable to an escalated privileges attack. The vulnerability caused systems that had both IIS and MDAC installed to give an unauthorized web user the ability to execute shell commands on the IIS system as a privileged user. This allowed the attacker to use MDAC to tunnel SQL and other ODBC data requests through the public connection to a private back-end network when on a multi-homed Internet-connected IIS system. It also allowed the user to gain unauthorized access to secured, non-published files on the IIS system[38]
When opening ArcCatalog or browsing a directory which includes text files, the following error message may occur:"Error reading textfile data. This could be due to corrupt ODBC/MDAC components. You may not have access to all the MDAC utilities you require. Please refer to the FAQ for further information".This may also cause ArcCatalog or ArcMap to crash with an application error.
Warning:The instructions below include making changes to essential parts of your operating system. It is recommended that you backup your operating system and files, including the registry, before proceeding. Consult with a qualified computer systems professional, if necessary.Esri cannot guarantee results from incorrect modifications while following these instructions; therefore, use caution and proceed at your own risk.Re-register the msadce.dll file. This is usually located in C:\Program Files\Common Files\System\MSADC.
If that does not solve the problem on a Windows NT platform, re-install the MDAC (2.5) pack. This (and other MDAC packs) can be downloaded from
If re-registering msadce.dll did not solve the problem on a Windows 2000 machine, installing Windows 2000 SP1 and upgrading MDAC to version 2.6 may be required.(As MDAC are installed as system components under Windows 2000 they can not be un-installed without replacing operating system files that were upgraded by the MDAC installer.) Please consult the release manifest and specification for MDAC 2.6 before proceeding. There may be some issues with the latest version of MDAC that you should be aware of.
IMPORTANT: You must have version 2.6 or higher of Microsoft Data Access Components (MDAC) installed to configure and use the Connect ADO data providers. You can download a utility that determines the version of your currently installed MDAC from the following Microsoft site:
If you do not have a supported version of MDAC, you can download it from this site or install it from the DataDirect CD. To install from the DataDirect CD, navigate from the root directory to \mdac and run mdac_typ.exe.
To use the SQL Server data provider, you must have the appropriate Microsoft SQL Server DB-Library and Net-Library version installed (version 6.0 for access to 6.0 DBMS; version 6.5 for access to 6.5 DBMS).
Connect ADO for Oracle7 can be used to access remote Oracle 7.x databases. You can create and configure a data source without the client software. However, to connect to the Oracle7 data source, the appropriate DLLs for the current version of SQL*Net must be on your path. The Oracle7 provider is supported in the Windows environments using the Oracle7 client.
To determine client software requirements, see your database vendor's documentation. To access supported remote Informix databases through the Informix data provider, you need Informix Connect for Windows platforms, version 2.x, or the Informix Client Software Development Kit for Windows platforms, version 2.x.
This version of the Component Checker has a dependency on MSXML2.dll. Users who do not have this dll on their machine will be prompted to visit www.microsoft.com/downloads to install MSXML 3.0 SP4 on their machines.
To install ODBC on Microsoft Windows three components are required to access the PostgreSQL Database server. Firstly you require the Microsoft Data Access Components (MDAC). This can be downloaded from :- Here you will find free downloads for all of the MDAC releases. These downloads are redistributable according to the End User License Agreements posted with each release. Eight releases of MDAC are available here: MDAC 2.7, two of MDAC 2.6, three of MDAC 2.5, and two of MDAC 2.1. You can also find several release manifests. Also please look at the information about installing MDAC. MDAC 2.7 RTM Refresh (2.70.9001.0) is the version which I downloaded from this site. This release contains the same version of the MDAC components that are installed by Windows XP. Secondly also download the recently updated Component Checker tool from this page. This release includes updated snapshots for MDAC 2.6 SP2 and MDAC 2.7 Refresh releases (filename cc.exe)Thirdly go to :- Download the latest version of psqlodbc-xx_yy_zzzz.zip where xx and yy are the same as the version of PostgreSQL in use (version 7.2 xx=07 and yy=02). The number zzzz is the release number of psqlodbc. I have currently installed from the psqlodbc-07_02_0001.zip file.
If you are using Access 2000, get and install the newest (version 2.6 or higher) Microsoft MDAC (Microsoft Data Access Components) from -in/download/details.aspx?id=21995. This fixes a bug in Access that when you export data to MySQL, the table and column names aren't specified.
Check the WinMSS About window. It also reports the current version of the Microsoft Jet Engine installed in the computer that WinMSS is being run on (not the computer that the WinMSS executable is installed on). If you Microsoft Jet Engine version are a lower version than 4.0.6218.0, you need to upgrade that computer with Jet 4.0 Service Pack 7. You may download this from here: =/downloads/list/dataaccess.asp
Note: Current versions of MDAC for all 32-bit Windows operating systems are available from Microsoft's Universal Data Access, Free Downloads, web page: If you encounter unusual database problems, compacting and repairing it or downloading and installing the Microsoft MDAC 2.7 SP 1 Refresh usually makes them go away.
MoneyCare + is available with MDAC and without MDAC. MoneyCare + without MDAC is provided to save download time. Generally, this component is required as a part of database storage using MS Access in database (user inputs or entries) storage needed programs.In operating systems Windows 2000 or higher (ME, XP), Microsoft Data Access Component (MDAC 2.6) or higher is already installed. So no need of installing this component separately. If you have downloaded MoneyCare + version without MDAC, make sure MDAC 2.6 or higher is installed in the system prior to the installation of MoneyCare +, especially in Windows 9X and NT. You may download MoneyCare + version with MDAC from our website. Alternatively, You may download Microsoft Data Access Component 2.6 (MDAC 2.6) or higher versions from Product and Update Downloads section in the Microsoft website. Free Download may take around 10 minutes using 10 Kbps transfer rate (may vary according to speed and other periodic changes). 2ff7e9595c
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