Lecture
All server-based DBMS have a client part that accesses the database through a DBMS. There is no direct connection between the client application and the DBMS, and software modules are additionally embedded that allow the client application to access the database created using different DBMS. Such modules are called data access mechanisms.
There are two main ways to access data from client applications: using the application interface and using the universal software interface.
An application programming interface (API - Application Programming Interface) is a set of functions that are called from a client application. It can work only with the DBMS of this manufacturer, and when replacing it, you will have to rewrite a significant part of the client application code. The application programming interface is different for different DBMS.
The universal data access mechanism provides the ability to use the same interface to access different types of DBMS. Usually it is implemented in the form of special additional modules, called drivers.
The most common software interface that provides data access to a specific database is Microsoft’s Open Database Connectivity (ODBC). As part of ODBC, a software application directly interacts with the dispatcher driver, sending it ODBC calls. The driver manager is responsible for dynamically loading the required ODBC driver through which it accesses the database server. The ODBC driver makes all calls to the ODBC functions and "translates" them into the data source language. The DBMS stores and outputs data in response to requests from the ODBC driver.
Setting the ODBC data source is an action that is performed by the operating system using a computer. In the Windows operating system, the Control Panel contains the item ODBC Data Sources (32 bits) from which the ODBC Data Source Administrator is called. It can be used to set:
- user DSN - data source accessible only to the current user on the current computer;
- file DSN - a source of data that can be shared by different users who have the same ODBC drivers installed;
- system DSN - data source accessible to all users and services of the current computer.
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Databases, knowledge and data warehousing. Big data, DBMS and SQL and noSQL
Terms: Databases, knowledge and data warehousing. Big data, DBMS and SQL and noSQL