The Relational Data Model Prakan Sringam Relational Data Slides: 14 Download presentation The Relational Data Model Prakan Sringam Relational Data Model แบบจำลองขอมลเชงสมพนธ • Relation รเลชน • Properties of Relation คณสมบตของ • Key Relation Relation Table-oriented ����� Table Set-oriented Record-oriented ������ File Relation ��� Row ������� Tuple ������� Record ����������� Field Column Attribute Key มอะไรบาง • • • Super Key Candidate Key Primary Key Alternate Key Foreign Key Super Key std. ID 5401001 5401002 5401003 std. Name std. Major ��������� ������ std. ID, std. Name std. ID, std. Major std. ID, Std. Name, Std. Major Primary Key • Key ทถกเลอกจาก คยหลก std. ID 5401001 5401002 5401003 std. ID Candidate เพอใชเปน std. Name std. Major std. SSN 123456781 ��������� �� 123456782 ��������� �� 123456783 ��������� ��� �� Alternate Key • Key ทไมถกเลอกจาก คยหลก std. ID 5401001 5401002 5401003 std. SSN Candidate เพอใชเปน std. Name std. Major std. SSN 123456781 ��������� �� 123456782 ��������� �� 123456783 ��������� ��� �� Foreign Key std. ID 5401001 5401002 5401003 std. Name major. Code ������� 1 1 ������ major. Code 1 2 3 Major. Name ������ ����� The limited tuple relational calculus equals:Relational calculusRelational calculus symbolsObject relational and extended relational databasesRelational algebra and calculusMapping of er model to relational modelWhat is the logical view of data?Extended relational data modelHát kết hợp bộ gõ cơ thểThẻ Bổ thểTỉ lệ cơ thể trẻ emGấu đi như thế nàoChụp phim tư thế worms-bretonBài hát chúa yêu trần thế alleluia