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19. What is an Extension of entity type? 20. What is Weak Entity set? 21. What is an attribute? 22. What is a Relation Schema and a Relation? A relation Schema denoted by R(A1, A2, ..., An) is made up of the relation name R and the list of attributes Ai that it contains. A relation is defined as a set of tuples. Let r be the relation which contains set tuples (t1, t2, t3, ..., tn). Each tuple is an ordered list of n-values t=(v1,v2, ..., vn). 23. What is degree of a Relation? 24. What is Relationship? 25. What is Relationship set? 26. What is Relationship type? 27. What is degree of Relationship type?
28. What is DDL (Data Definition Language)? A data base schema is specifies by a set of definitions expressed by a special language called DDL. 29. What is VDL (View Definition Language)? 30. What is SDL (Storage Definition Language)? 31. What is Data Storage - Definition Language? 32. What is DML (Data Manipulation Language)? 1.Procedural DML or Low level:DML requires a user to specify what data are needed and how to get those data. 2.Non-Procedural DML or High level:DML requires a user to specify what data are needed without specifying how to get those data. 33. What is DML Compiler?