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Relational Model and Concepts

relational and concepts

balachandran
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Relational Model and Concepts

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  1. Relational Model and concepts KRISHNA .B

  2. Contents • Tables • Relational Model • Features of Relational Model • Concepts of Relational Model 1 Attributes 2 Rows 3 Domain 4 Degree of Relation 5 Cardinality of Relation • Theorem of Relational Model

  3. Tables There are the collection of rows and columns . Or intersection of rows and columns is called tables. Tables are also known as relation.

  4. Relational Model A Relational Model is a model which manage all the tables in the database and performs in the database and performs the related activities It was developed by Edgar F Codd.

  5. Features of Relational Model • All the columns are homogenous in nature. • Every row is unique • Order of columns is not important • Order of rows is not important

  6. Concepts of Relational Model • Attributes • Rows • Domain • Degree of relation • Cardinality of relation

  7. Attributes Features of an entity are called Attributes.

  8. Rows The instance inside the table are called Rows.

  9. Domain By domain we mean the data type of column.

  10. Degree of Relation The number of columns in a table specifie the degree.

  11. Cardinality of Relation The number of rows in a table specifies the cardinality of a table.

  12. Theorem of Relational Model • Suppose we have a relation R=(A1,A2,A3,A4…..) where A1,A2 are the Attributes of the table. • Every attribute ai has a domain given as dom (ai) • The relation R contains (t1,t2,t3…) where t1,t2 are tuples • Every tuples ti contains (V1,V2,V3…) where V1,V2 are the values

  13. THANK YOU

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