A database application is not a single product or a solution. A database can be considered as a combination of methodologies and techniques can provide a pragmatic and efficient approach to dealing with the problem of user-friendliness and accessibility to important information that has been disseminated across the organization. As an organization changes its requirements to further, the database applications that depend upon them should also change.
Modern database modeling tools now support ER modeling techniques which help in developing and building collaboration and common relationship between different entities of a database system. ER modeling focuses on normalizing the database structure. ER modeling is quite effective in the case of an Online Transaction Processing (OLTP). The OLTP helps in building and maintaining the data integrity during and after the database transactions. Decision support systems are built further away from the general concept of data modeling and OLTP. These decision support systems use data warehousing and data mart techniques which can support OLTP and is an efficient use of normalization. Data warehouses and marts can only provide support information for final decision support systems.
Decision-making and support systems extract data from different OLTPs/external sources and further organized as per fact/s or burning question/s for decision-making purposes.
Two-tier database development consists of two layers. In this type of database design, the clients directly talk to server. The business logic is considered as data logic as well. Two tier applications have lesser coding times which can be of great use but its inability to add distinct users for application layer with different platforms make it unfavorable solution for larger companies. Two-tier database design is good for small companies with 50 – 60 clients. Some database systems use stored procedures as a method to facilitate the programming which works as a virtual third tier.
The true three tier application requires three layers where the middle layer contains the actual business logic and methods necessary to operate the application. The client layer is totally different and acts as a front end only which can be changed according to geographical location or language and platform requirements. Three-tier applications need more programming time but are more stable, flexible and their ability to integrate with new clients is really remarkable which is the most important advantage in itself.
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