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    • Relational Model
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    • Types of Keys in Relational Model
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  1. Relational Model

Facts About Relational Model

  1. Relational Model (RM) organises the data in the form of relations (tables).

  2. A relational DB consists of collection of tables, each of which is assigned a unique name.

  3. A row in a table represents a relationship among a set of values, and table is collection of such relationships.

  4. Tuple: A single row of the table representing a single data point / a unique record.

  5. Columns: represents the attributes of the relation. Each attribute, there is a permitted value, called domain of the attribute.

  6. Relation Schema: defines the design and structure of the relation, contains the name of the relation and all the columns/attributes.

  7. Common RM based DBMS systems, aka RDBMS: Oracle, IBM, MySQL, MS Access.

  8. Degree of table: number of attributes/columns in a given table/relation.

  9. Cardinality: Total no. of tuples in a given relation.

  10. Relational Key: Set of attributes which can uniquely identify an each tuple.

  11. Important properties of a Table in Relational Model :

    1. The name of relation is distinct among all other relation.

    2. The values have to be atomic. Can’t be broken down further.

    3. The name of each attribute/column must be unique.

    4. Each tuple must be unique in a table.

    5. The sequence of row and column has no significance.

    6. Tables must follow integrity constraints - it helps to maintain data consistency across the tables

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