4 March 2014

Explaining about ActiveX Data Objects (ADO)?

ActiveX Data Objects (ADO) is a collection of software components providing a programmatic interface to access the data sources from client applications.
                                                     ADO acts as a layer to access any data store in a generic way from the application code. It eliminates the need to possess the knowledge of database implementation and reduces the complexity of dealing with the low level code needed to handle the data.

Released in 1996, activeX data object (ADO) originated from the concept of RDO (remote data object) and DAO (data access object). One of the constituents of MDAC (Microsoft data access components), ADO and other MDAC constituents provides a framework of components used by client applications to access SQL, semi-structured and legacy data stores.

ADO.NET is an advanced data access technology designed to work in the .NET environment and is based on the disconnected model for data access. While ADO uses COM (Component Object Model) technology for providing data access service from unmanaged code, ADO.NET depends on managed providers of the CLR (Common Language Runtime) of the .NET framework.

ADO uses an OLEDB provider for connecting to the data sources and accessing data. OLEDB is a component based programmatic interface provided to interact with different data sources. These data sources can be both relational and non-relational databases such as object databases, web pages, spreadsheets or e-mail messages. Prior to OLEDB and ADO, ODBC (open database connectivity) was the popular model used in applications across platforms.

The object model of ADO contains four collections of 12 objects.
The different collections are fields, properties, parameters and errors.

Each collection consists of the following 12 objects:
Connection - for connecting to data source through OLE DB
Command - for sending an instruction (SQL query or stored procedure) to data provider
Recordset - a group of records representing the data
Immediate - a recordset locked in optimistic or pessimistic way
Batch - for committing or doing a rollback database transaction
Transaction - the database transaction
Record - a set of fields
Stream - for reading and writing a stream of bytes
Parameter - for changing the functionality
Field - a column in the database
Property - the ability of OLEDB provider
Error - the error faced by the OLEDB provider during its execution

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