38. An Example CREATE TABLE Student ( ID NUMBER, Fname VARCHAR2(20), Lname VARCHAR2(20), );
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40. Not Null Constraint CREATE TABLE Student ( ID NUMBER, Fname VARCHAR2(20) NOT NULL , Lname VARCHAR2(20) NOT NULL , );
41. Primary Key Constraint Primary Key implies: * NOT NULL * UNIQUE. There can only be one primary key. CREATE TABLE Student ( ID NUMBER PRIMARY KEY , Fname VARCHAR2(20) NOT NULL, Lname VARCHAR2(20) NOT NULL, );
42. Primary Key Constraint (Syntax 2) CREATE TABLE Students ( ID NUMBER, Fname VARCHAR2(20) NOT NULL, Lname VARCHAR2(20) NOT NULL, PRIMARY KEY(ID) ); Needed when the primary key is made up of two or more fields
43. Another Table CREATE TABLE Studies( Course NUMBER, Student NUMBER ); What additional constraint do we want on Student? What should be the primary key?
44. Foreign Key Constraint NOTE: ID must be unique (or primary key) in Student CREATE TABLE Studies( Course NUMBER, Student NUMBER, FOREIGN KEY (Student) REFERENCES Students(ID) );
51. Translating Recursive Relationships (without constraints) Employee id name address Manages manager worker Relation: Actor ( worker-id , manager-id ) What would be the table definition?
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Hinweis der Redaktion
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3 The slides for this text are organized into several modules. Each lecture contains about enough material for a 1.25 hour class period. (The time estimate is very approximate--it will vary with the instructor, and lectures also differ in length; so use this as a rough guideline.) This covers Lectures 1 and 2 (of 6) in Module (5). Module (1): Introduction (DBMS, Relational Model) Module (2): Storage and File Organizations (Disks, Buffering, Indexes) Module (3): Database Concepts (Relational Queries, DDL/ICs, Views and Security) Module (4): Relational Implementation (Query Evaluation, Optimization) Module (5): Database Design (ER Model, Normalization, Physical Design, Tuning) Module (6): Transaction Processing (Concurrency Control, Recovery) Module (7): Advanced Topics
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