A data schema is the structure or blueprint of a database. It defines the organization, storage, and relationships among data elements, tables, views, and other database objects. The schema provides a framework for organizing data and ensuring data integrity and consistency.
A data schema typically includes a description of each data element or attribute, such as its data type, size, and format. It also defines the relationships among the tables or views, including the primary and foreign keys used to connect them. In addition, the schema may define views, stored procedures, and other database objects.
The schema is usually created using a data definition language (DDL), such as SQL, and is stored in the database catalog. It is important to note that the schema can be modified as needed to accommodate changes in the data or business requirements.
Common types:
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Entity-Relationship (ER) schema: This type of schema defines the entities or objects in the database, as well as their attributes and relationships.
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Relational schema: This type of schema defines the tables, columns, and relationships in a relational database.
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Object-oriented schema: This type of schema defines the objects, classes, and inheritance relationships in an object-oriented database.
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Document schema: This type of schema defines the structure and relationships of documents in a document-oriented database.