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Limitations Hierarchical organization technology does not involve many. To many relationships which means that the data storage system is quite limite. Network databases This technology develops a hierarchical approach by modeling complex relationships between objects. Here children can have more than one parent but the limitations of the hierarchical approach remain. Network database An example of a network database. Example IDMS is a specialize DBMS for mainframes. Relational databases This type of database is the oldest the theoretical foundations of the approach were laid by the British scientist egar Codd in.

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Here the data is forme into tables of rows and columns. The rows contain information about the objects property values and the columns contain the properties of the objects themselves fields . Normalization Complex relationships of objects in relational databases are Dubai Email List modele using foreign keys links to other tables. This allows you to approach the issue of database design from the standpoint of normalization minimizing reundancy in describing the properties of objects. For example if we are talking about a restaurant menu then each dish has a weight price name calorie content and the category to which it belongs hot appetizers cold appetizers first courses desserts salads and so on.

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The relationship between dishes and category is done through the category index reference field in the dish table. This approach allows Minimize the size of the database you do not nee to prescribe a category name for each dish. Improve system integrity BM Leads In the above example all dishes are linke to menu categories. Adding a dish without a category is impossible as well as specifying an index of a non existent category as a link. Simplify scaling new dishes can be adde to existing categories. Also adding new categories linking new dishes to them and reistributing dishes into categories is not exclude.

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