Relational Database Model

• Relational Model: represents the database as a collection of relations. A relation is nothing but a table of values. Every row in the table represents a collection of related data values. These rows in the table denote a real-world entity or relationship.
• Relational Model Concepts

  Attribute: Each column in a Table. Are the properties which define a relation. E.g., Student_Rollno, NAME, etc.
• Relational Model Concepts

  Tables: In the Relational model, the relations are saved in the table format. It is stored along with its entities. A table has two properties rows and columns. Rows represent records and columns represent attributes.
• Relational Model Concepts

  Tuple: It is nothing but a single row of a table, which contains a single record.
• Relational Model Concepts

  Relation Schema: Represents the name of the relation with its attributes.
• Relational Model Concepts

  Degree: The total number of attributes which in the relation.
• Relational Model Concepts

  Cardinality: Total number of rows present in the Table.
• Relational Model Concepts

  Column: represents the set of values for a specific attribute.
• Relational Model Concepts

  Relation instance: is a finite set of tuples in the RDBMS system. Never have duplicate tuples.
• Relational Model Concepts

  Relation key: Every row has one, two or multiple attributes.
• Relational Model Concepts

  Attribute domain: Every attribute has some pre-defined value and scope which is known as attribute domain.
• Relational Integrity Constraints in DBMS are referred to conditions which must be present for a valid relation. These are derived from the rules in the mini-world that the database represents.
• Types of Integrity Constraints

  Domain Constraints: can be violated if an attribute value is not appearing in the corresponding domain or it is not of the appropriate data type.
• Types of Integrity Constraints

  Key Constraints: an attribute that can uniquely identify a tuple in a relation. The value of the attribute for different tuples in the relation has to be unique.
• Referential Integrity Constraints: are based on the concept of Foreign Keys. A foreign key is an important attribute of a relation which should be referred to in other relationships.
• Operations in Relational Model

  Insert: gives values of the attribute for a new tuple which should be inserted into a relation.
• Operations in Relational Model

  Delete: used to delete tuples from the table.
• Operations in Relational Model

  Update: allows you to change the values of some attributes in existing tuples.
• Operations in Relational Model

  Select: allows you to choose a specific range of data.