1. IT 20303 The Relational DBMS Section 07

2. Relational Database Theory Using a Relational DBMS

3. Data Types –Depends on the conventions used by a particular database –ORACLE uses: NUMBER CHAR - Characters VARCHAR2 -Characters DATE/TIME LOB Relational Database Theory

4. NUMBERNUMBER –Numerical data –Guaranteed to 38 digits accuracy –NUMBER(10) – 10 digits allowed CHARCHAR –Character data –Fixed-Length up to 2,000 bytes –Good for 2 or 3 characters –Y/N, T/F, USA/CAN –CHAR(2) – 2 characters allowed Relational Database Theory

5. VARCHAR2 –Character data –Variable-Length up to 4,000 bytes –VARCHAR2(15) – up to 15 characters DATE/TIME –Date & Time data –DATE – DD-MON-YY (Default) –TIME – HH:MN:SE (Default) Relational Database Theory

6. LOBLOB –Large OBject data type CLOBCLOB –Long variable length characters BLOBBLOB –Binary objects – Video, Sound, Graphics BFILEBFILE –Reference to an OS file –Up to 4GB of data per file Relational Database Theory

7. SQL: Structured Query Language –Command-driven, nonprocedural language –Origin: IBM, System R, Mid-1970s, SEQUEL (SQL) –Adopted by Oracle in late 1970s Before IBM product –State of the art (state of the art does not mean ideal)

8. Relational Database Theory SQL Standards –Major standards organizations work together American National Standards Institute (ANSI) International Organization for Standardization (ISO)

9. Relational Database Theory SQL Standards –More than 25 approved and current standards SQL language: verbs, concepts, clauses, operations Embedding SQL in host language Persistent stored modules (stored procedures) SQL routines using JAVA On-Line analytical processing

10. Relational Database Theory Structured Query Language –DDL – Data Definition Language CREATE DROP ALTER

11. Relational Database Theory Structured Query Language –DML – Data Manipulation Language SELECT INSERT DELETE UPDATE

12. Relational Database Theory Structured Query Language –DCL – Data Control Language GRANT REVOKE

13. Relational Database Theory Characteristics of SQL –Capabilities to Define database objects – DDL –Tables, Views, Indexes, Users, Constraints Manipulate Data – DML –Query capability based on relational algebra set operations –Update capability Control Data - DCL

14. Relational Database Theory Characteristics of SQL –Intended for use by DBA Application Developers Some End Users –SQL is easily grasped, but not quickly mastered (Croft, 1990)

15. Relational Database Theory Example: DEPT table DEPTNODNAMELOC 10ACCOUNTINGCHICAGO 20RESEARCHLONDON 30SALESLOS ANGELES 40OPERATIONSBOSTON DEPT EMPLOYEE DEPARTMENT Supervises Works for

16. Relational Database Theory EMPNOENAMEJOBMGRHIREDATESALCOMMDEPTNO 7369SMITHCLERK790217-DEC-199880020 7499ALLENSALESMAN769820-FEB-2000160030030 7521WARDSALESMAN769822-FEB-1998125050030 7566JONESMANAGER783902-APR-1995297520 7654MARTINSALESMAN769828-SEP-19971250140030 7698BLAKEMANAGER783901-MAY-1993285030 7782CLARKMANAGER783909-JUN-1999245010 7788SCOTTANALYST756609-DEC-1996300020 7839KINGPRESIDENT17-NOV-1991500010 7844TURNERSALESMAN769808-SEP-19921500030 7876ADAMSCLERK778812-JAN-1997110020 7900JAMESCLERK769803-DEC-199995030 7902FORDANALYST756603-DEC-1994300020 7934MILLERCLERK778223-JAN-2000130010 EMP Example: EMP table

17. Relational Database Theory Table Definition: ANSI SQL –CREATE TABLE DEPT (deptnoNUMBER(2) NOT NULL, dname VARCHAR2(14), loc VARCHAR2(13) DEFAULT ‘Key West’);

18. Relational Database Theory Table Definition: ANSI SQL –CREATE TABLE EMP (empno NUMBER(4) NOT NULL, ename VARCHAR2(10), job VARCHAR2(10), mgrNUMBER(4), hiredateDATE, salNUMBER (7,2), commNUMBER (7,2), deptnoNUMBER(2) NOT NULL);

19. End 10-10-05

20. Relational Database Theory Data Definition Statements –Define Table structure and constraints –CREATE TABLE makes entries in the data dictionary Table Name Attributes –Name, Datatype, Size, Nullability Constraints –Primary Key –Foreign Key –Check Clause –ALTER TABLE updates the data dictionary Adds or modifies attributes Adds or modifies constraints –DROP TABLE removes entries from the data dictionary

21. Relational Database Theory The System Tables –Also called data dictionary, catalog –System tables are tables – just like the data tables For example: –user_tables –user_constraints –user_indexes

22. Relational Database Theory The System Tables –System tables are queried by DBAs and Users via SQL DBAs can write procedures, reports using system tables Graphical DBA tools generate SQL to access the dictionary

23. Relational Database Theory The System Tables –RDBMS accesses the system tables on every SQL request Updated by DDL statements Referenced on DML statements

24. Relational Database Theory SQL: SELECT is used for all queries –SELECTData Items –FROMTable(s) –WHERECondition is True

25. Relational Database Theory Manipulation: SELECT Example –Example 01: SELECT * FROM EMP WHERE job = ‘ANALYST’; Results EMPNOENAMEJOBMGRHIREDATESALCOMMDEPTNO 7788SCOTTANALYST756609-DEC-1996300020 7902FORDANALYST756603-DEC-1994300020

26. Relational Database Theory Manipulation: SELECT Example –Example 02: SELECT ename, job, hiredate FROM EMP WHERE hiredate > ’31-DEC-99’; Results ENAMEJOBHIREDATE ALLENSALESMAN20-FEB-2000 MILLERCLERK23-JAN-2000

27. Relational Database Theory Manipulation: SELECT Example –Example 03: SELECT empno, ename, loc FROM EMP, DEPT WHERE emp.deptno = dept.deptno AND loc = ‘CHICAGO’; Results EMPNOENAMELOC 7782CLARKCHICAGO 7839KINGCHICAGO 7934MILLERCHICAGO

28. Relational Database Theory Manipulation: SELECT Example –Class Practice 01: –Give me a list of all the salesman and their managers? –SELECT ename, job, mgr –FROM EMP –WHERE job = ‘SALESMAN’;

29. Relational Database Theory Manipulation: SELECT Example –Class Practice 02: –Give me a list of all clerks to include their employee number, manager, hiredate and salary for those who make more than $1000? –SELECT empno, ename, mgr, hiredate, sal –FROM emp –WHERE job = ‘CLERK’ AND sal > 1000;

30. Relational Database Theory Manipulation: SELECT Example –Class Practice 03: –Give me a list of employees who work in the accounting department including their salaries? –SELECT ename, sal, dname –FROM emp, dept –WHERE emp.deptno = dept.deptno –AND deptno = 10;

31. Relational Database Theory SELECT is used to Read Data –User “Designs” the query Expresses it according to SQL syntax –One SELECT query can request multiple relational algebra operations SELECT….which columns FROM….which tables WHERE….which rows –Each SELECT query is optimized Transformed into a query execution plan

32. Relational Database Theory SQL: SELECT…ORDER BY –SELECTData Items –FROMTable(s) –WHERECondition is True –ORDER BYData Item [DESC | ASC] –Presents the result set in sorted order

33. Relational Database Theory SQL: SELECT…ORDER BY –Example: –SELECT empno, ename, sal –FROM emp –WHERE sal > 2500 –ORDER BY sal; EMPNOENAMESAL 7698BLAKE2850 7566JONES2975 7788SCOTT3000 7902FORD3000 7839KING5000

34. Relational Database Theory SELECT can present Derived Values –List all the analysts, showing their annual compensation –SELECT empno, ename, 12*sal –FROM emp –WHERE job = ‘ANALYST’; EMPNOENAME12*SAL 7788SCOTT36000 7902FORD36000

35. End 10-12-05

36. Relational Database Theory SQL Subqueries –Suppose we want to find out who makes more money than Jones We could first find out Jones’ salary Then find all employees whose salary is greater than that Alternatively…SQL allows nesting subqueries

37. Relational Database Theory SQL Subqueries –Example: –SELECT empno, ename –FROM emp –WHERE sal > (SELECT sal FROM emp WHERE ename = ‘JONES’); The subquery is executed first

38. Relational Database Theory Updating the Database –INSERT Append new rows to a table Example: INSERT INTO dept (deptno, dname, loc) VALUES (40, ‘OPERATIONS’, ‘BOSTON’);

39. Relational Database Theory Updating the Database –DELETE Removes one or more rows from a table Example: DELETE FROM dept WHERE loc = ‘DETROIT’;

40. Relational Database Theory Updating the Database –UPDATE Replaces values in one or more columns Example: UPDATE emp SET sal = sal * 1.10 WHERE ename = ‘MILLER’;

41. Relational Database Theory SQL Query and Manipulation Summery (ANSI Standard) Reading –SELECT Updating –INSERT –DELETE –UPDATE

42. Relational Database Theory SQL Query and Manipulation Summery (ANSI Standard) Grouping –GROUP BY –HAVING Sequencing –ORDER BY

43. Relational Database Theory SQL Query and Manipulation Summery (ANSI Standard) Built-in Functions –MIN –MAX –SUM –AVG –COUNT –DISTINCT

44. Relational Database Theory SQL Query and Manipulation Summery (ANSI Standard) Special Operators –NOT, AND, OR –BETWEEN, NOT BETWEEN –IN, NOT IN –LIKE, NOT LIKE –IS NULL, IS NOT NULL

45. Relational Database Theory SQL Query and Manipulation Summery (ANSI Standard) Arithmetic Operators –+ –- –/ –*

46. Relational Database Theory SQL Query and Manipulation Summery (ANSI Standard) Comparison Operators –= –<> (not equal) –< –> –<= –>=

47. Relational Database Theory Views –Purpose of Views Simplify Function Security

48. Relational Database Theory View Definition –CREATE VIEWview_name AS SELECTdata_items FROMtable(s) WHEREcondition is true –View definition is saved in system tables –View is a Virtual Table Database is accessed only when view is referenced

49. Relational Database Theory View Definition Cont’d –Each user “sees” the database through their view as if It is only one table It contains only the data items of interest The data items of interest have that user’s names The data items are in exactly the order desired Multiple views can be based on the same table

50. Relational Database Theory View Example –Create a view for the accounting department to include: empno, ename, position, ancomp CREATE VIEW acct (empno, ename, position, ancomp) AS –SELECT empno, ename, job, 12*(sal+nvl(comm, 0)) –FROM emp;

51. Relational Database Theory View Example –List all the analysts showing their annual compensation SELECT * FROM acct WHERE position = ‘ANALYST’; –Here the Query and View are merged for query execution

52. Relational Database Theory Updating through Views –Update through view modifies data in the underlying table Updates can be made through views based on one table Updates can sometimes be made through views based on more than one table –UPDATE acct –SET position = ‘SALESMAN’ –WHERE ename = ‘JAMES’;

53. Relational Database Theory Database Security is based on Password and Authorizations –Need is to protect the database from unauthorized users –Authorization is granted to individual users to Access (log on to) the DBMS Access specified attributes in the database Execute specified operations on each attribute –The DBA is responsible for Passwords, and Authorizations

54. Relational Database Theory The Role of the DBA –DBA privileges vary greatly from product to product –Users can GRANT privileges on a table provided: User is the owner, executed CREATE TABLE for that table or User was granted privileges WITH GRANT OPTION

55. Relational Database Theory The Role of the DBA –DBA has permissions to execute other statements Can CREATE, DROP, or ALTER users, user profiles, tablespaces, tables, etc –Some installations create a hierarchy of DBAs Entire Database Application area DBAs –Good practice is to create a user_id for each specific DBA role

56. Relational Database Theory DCL – Data Control Language –Commands: GRANT REVOKE

57. Relational Database Theory Security and SQL –GRANT statement GRANTprivileges ONa table or view TOa user (WITH GRANT OPTION) –REVOKE statement REVOKEprivileges ONa table or view FROMa user

58. Relational Database Theory ANSI SQL GRANT privileges –ALL –SELECT –INSERT –UPDATE –DELETE –CONNECT

59. Relational Database Theory See Example data for Employee & Departments: –Let Miller read all of the EMP table –Part 01 GRANT Connect TO miller IDENTIFIED BY 382miller; –Part 02 GRANT Select ON emp TO miller;

60. Relational Database Theory See Example data for Employee & Departments: –Let Jones read and update the data for employees in her department –Part 01 CREATE VIEW jones AS SELECT * FROM emp WHERE mgr = 7566;

61. Relational Database Theory See Example data for Employee & Departments: –Part 02 GRANT Select, Update ON jones TO jones;

62. Relational Database Theory See Example data for Employee & Departments: –Let King read the data for all employees in the emp table and update the salary, commission, and job attributes. GRANT Select, Update(sal, comm, job) ON emp TO king;

63. Relational Database Theory Database Security: –Security is a mentality –Security is environment-specific –The DBA has a key role Builds the database Grants user/password access into DBMS Defines user views Grants user access and authorization to data –95% of all security violations can be avoided by attention to detail Change master passwords after installation Change passwords frequently

64. Relational Database Theory Questions?