What is a Database Schema?

An article by Jorge Reis    2 Comments

Database schema refers to the layout of the database, which shows how each data is organized into structures or tables. It is also referred to as the language used by database management systems. The schema in a relational database refers to the tables, fields and also the existing relationship between the fields and tables. Schemas are stored in a data dictionary, and although it is usually in database language, it is considered as the graphic model of a database. Simply put, it is the representation of the database. Data dictionary, on the other hand, is the storage for the data input by various users. It can handle large quantities of information from multiple sources.

Understanding Database Schema

Another definition of a database schema is that it refers to the characteristics of an input. An example is the number of characters in a string for a field name or password, and this is considered a database schema. This includes the kind of characters allowed for the field name or password. It also talks about the relationship between the tables that are within a certain database. Schema is the term used when talking about the existing templates, such as the strings or characters that are required when adding information.

Database schema is also known as a repository of tables that are already defined along with their relationship with one another. Large numbers of object-oriented classes can be seen in a schema. Data types, assertions, and procedures that are stored can be included in a schema.

Levels of Database Schema and Its Functions

Database is simple enough to understand. The creation of it is another matter. There are different levels of a database schema that is required in creating a database. Each level represents different functions, and these are the conceptual schema, logical schema, and physical schema. Conceptual schema shows the concepts of the information placed in tables as well as their relationships. This usually talks about the semantics of a group. Conceptual schema refers to important matters related to the group or organization, its characteristics as well as their association with one another which is considered to be significant. The conceptual schema also allows a database to inherit a characteristic from another database. The meaning of inheritance leans more on object oriented terminology.

Logical schema, on the other hand, refers to the model of the data that talk about a specific problem in a domain that is a part of a database. It also refers to tables and columns that are in relation to one another, XML tags and classes that are object-oriented.

There is still a difference between the conceptual and physical schema. Once the logical schema is done, the next step, which is also the last step in creating a database, is the physical schema.

Physical schema refers to the storage of data into disk drives that can be used in a company whose computers are all in a network which is located within one place and yet still connected to another company in another area. Physical schema simply refers to how a series of networked computers are related to another network, which may be found in another area or possibly in another country.