1. 10/17/2000Database Management -- R. Larson Data Administration and Database Administration University of California, Berkeley School of Information Management and Systems SIMS 257: Database Management

2. 10/17/2000Database Management -- R. Larson Mid-Term Assignment #5 See WWW site: –http://sims.berkeley.edu/courses/is257/f00/index.htmlhttp://sims.berkeley.edu/courses/is257/f00/index.html Report on personal database including: –Database description –Data Dictionary –Relationships Diagram –Sample queries and results –Sample forms –Sample reports

3. 10/17/2000Database Management -- R. Larson Review Web enabled database systems

4. 10/17/2000Database Management -- R. Larson Why Use a Database System? Database systems have concentrated on providing solutions for many issues in scaling up Web applications –Performance –Scalability –Maintenance –Data Integrity –Transaction support While systems differ in their support, most offer some support for all of these.

5. 10/17/2000Database Management -- R. Larson Dynamic Web Applications 2 Server database CGI DBMS Web Server Internet Files Clients database

6. 10/17/2000Database Management -- R. Larson Server Interfaces DatabaseWeb Server Web Application Server Adapted from John P Ashenfelter, Choosing a Database for Your Web Site Web DB App HTML JavaScript DHTML CGI Web Server API’s ColdFusion PhP Perl Java ASP SQL ODBC Native DB interfaces JDBC Native DB Interfaces

7. 10/17/2000Database Management -- R. Larson What Database systems are available? Choices depend on: –Size (current and projected) of the application –Hardware and OS Platforms to be used in the application –Features required E.g.: SQL? Upgrade path? Full-text indexing? Attribute size limitations? Locking protocols? Direct Web Server access? Security? –Staff support for DBA, etc. –Programming support (or lack thereof) –Cost/complexity of administration –Budget

8. 10/17/2000Database Management -- R. Larson Desktop Database Systems Individuals or very small enterprises can create DBMS-enabled Web applications relatively inexpensively Some systems will require an application server (such as ColdFusion) to provide the access path between the Web server and the DBMS

9. 10/17/2000Database Management -- R. Larson Enterprise Database Systems Enterprise servers are powerful and available in many different configurations They also tend to be VERY expensive Pricing is usually based on users, or CPU’s

10. 10/17/2000Database Management -- R. Larson Free Database Servers System is free, but there is also no help line. Include many of the features of Enterprise systems, but tend to be lighter weight Versions may vary in support for different systems Open Source -- So programmers can add features

11. 10/17/2000Database Management -- R. Larson Embedded Database Servers May require programming experience to install Tend to be fast and economical in space requirements

12. 10/17/2000Database Management -- R. Larson Database Security Different systems vary in security support: –Views or restricted subschemas –Authorization rules to identify users and the actions they can perform –User-defined procedures (and rule systems) to define additional constraints or limitations in using the database –Encryption to encode sensitive data –Authentication schemes to positively identify a person attempting to gain access to the database

13. 10/17/2000Database Management -- R. Larson Web Application Server Software ColdFusion PHP ASP All of the are server-side scripting languages that embed code in HTML pages

14. 10/17/2000Database Management -- R. Larson ColdFusion Started as CGI –Drawback, as noted above, is that the entire system is run for each cgi invocation Split into cooperating components –NT service -- runs constantly –Server modules for 4 main Web Server API (glue that binds web server to ColdFusion service) {Apache, ISAPI, NSAPI, WSAPI} –Special CGI scripts for other servers

15. 10/17/2000Database Management -- R. Larson What ColdFusion is Good for Putting up databases onto the Web Handling dynamic databases (Frequent updates, etc) Making databases searchable and updateable by users.

16. 10/17/2000Database Management -- R. Larson Requirements Unix or NT systems Install as SuperUser Databases must be defined via “data source names (DSNs) by administrator

17. 10/17/2000Database Management -- R. Larson Requirements and Set Up Field names should be devoid of spaces. Use the underscore character, like new_items instead of "new items." Use key fields. Greatly reduces search time. Check permissions on the individual tables in your database and make sure that they have read-access for the username your Web server uses to log in. If your fields include large blocks of text, you'll want to include basic HTML coding within the text itself, including boldface, italics, and paragraph markers.

18. 10/17/2000Database Management -- R. Larson Templates cont. Contents of My Shopping Cart Contents of My Shopping Cart #Item# #Date_of_item# $#Price#

19. 10/17/2000Database Management -- R. Larson CFML ColdFusion Markup Language Read data from and update data to databases and tables Create dynamic data-driven pages Perform conditional processing Populate forms with live data Process form submissions Generate and retrieve email messages Perform HTTP and FTP function Perform credit card verification and authorization Read and write client-side cookies

20. 10/17/2000Database Management -- R. Larson PHP PHP is an Open Source Software project with many programmers working on the code. –Commonly paired with MySQL, another OSS project –Free –Both Windows and Unix support Estimated that more than 250,000 web sites use PHP as an Apache Module.

21. 10/17/2000Database Management -- R. Larson PHP Syntax Similar to ASP Includes most programming structures (Loops, functions, Arrays, etc.) Loads HTML form variables so that they are addressable by name <?php $myvar = “Hello World”; echo $myvar ; ?>

22. 10/17/2000Database Management -- R. Larson Combined with MySQL DBMS interface appears as a set of functions: <?php $db = mysql_connect(“localhost”, “root”); mysql_select_db(“mydb”,$db); $result = mysql_query(“SELECT * FROM employees”, $db); Printf(“First Name: %s \n”, mysql_result($result, 0 “first”); Printf(“Last Name: %s \n”, mysql_result($result, 0 “last”); ?>

23. 10/17/2000Database Management -- R. Larson ASP – Active Server Pages Another server-side scripting language From Microsoft using Visual Basic as the Language model (VBScript), though Javascript (actually MS Jscript) is also supported Works with Microsoft IIS and gives access to ODBC databases

24. 10/17/2000Database Management -- R. Larson ASP Syntax <% SQL="SELECT last, first FROM employees ORDER BY last" set conn = server.createobject("ADODB.Connection") conn.open “employee" set people=conn.execute(SQL) %> <% do while not people.eof set resultline=people(0) & “, “ & people(1) & “ ” Response.Write(resultline) people.movenext loop%>

25. 10/17/2000Database Management -- R. Larson Conclusions Database technology is a required component for large-scale dynamic Web sites, especially E-Commerce sites Web databases cover most of the needs of dynamic sites (except for text search) Many solutions and systems are available for web-enabled databases

26. 10/17/2000Database Management -- R. Larson Today Data Administration Database Administration

27. 10/17/2000Database Management -- R. Larson Terms and Concepts Data Administration –Responsibility for the overall management of data resources within an organization Database Administration –Responsibility for physical database design and technical issues in database management Data Steward –Responsibility for some subset of the organization’s data, and all of the interactions (applications, user access, etc.) for that data

28. 10/17/2000Database Management -- R. Larson Terms and Concepts DA –Data adminstrator - person responsible for the Data Administration function in an organization –Sometimes may be the CIO -- Chief Information Officer DBA –Database Administrator - person responsible for the Database Administration Function

29. 10/17/2000Database Management -- R. Larson Database System Life Cycle Operation & Maintenance Database Implementation Database Design Growth & Change Database Analysis Database Planning Note: this is a different version of this life cycle than discussed previously

30. 10/17/2000Database Management -- R. Larson Database Planning Development of a strategic plan for database development that supports the overall organization’s business plan. DA supports top management in development of this plan. The result of this stage is an enterprise data model.

31. 10/17/2000Database Management -- R. Larson Database Planning: DA & DBA functions Develop corporate database strategy (DA) Develop enterprise model (DA) Develop cost/benefit models (DA) Design database environment (DA) Develop data administration plan (DA)

32. 10/17/2000Database Management -- R. Larson Database Analysis This is the process (discussed previously) of identifying data entities currently used by the organization, precisely defining those entities and their relationships, and documenting the results in a form that can support the follow-on design phase. Must also identify new data elements or changes to data elements that will be required in the future. The result of this phase is the Conceptual Data Model -- usually represented as an ER diagram.

33. 10/17/2000Database Management -- R. Larson Database Analysis: DA & DBA functions Define and model data requirements (DA) Define and model business rules (DA) Define operational requirements (DA) Maintain corporate Data Dictionary (DA)

34. 10/17/2000Database Management -- R. Larson Database Design Purpose of the design phase is the development of the logical database design that will serve the needs of the organization and the physical design implementing the logical design. In relational systems the outcome is normalized relations, and the data definition for a particular database systems (including indexes, etc.)

35. 10/17/2000Database Management -- R. Larson Design 2: Physical Creation Development of the Physical Model of the Database –data formats and types –determination of indexes, etc. Load a prototype database and test Determine and implement security, privacy and access controls Determine and implement integrity constraints

36. 10/17/2000Database Management -- R. Larson Database Design: DA &DBA functions Perform logical database design (DA) Design external models (subschemas) (DBA) Design internal model (Physical design) (DBA) Design integrity controls (DBA)

37. 10/17/2000Database Management -- R. Larson Database Implementation Database design gives you an empty database Load data into the database structure Convert existing data sets and applications to use the new database –May need programs, conversion utilities to convert old data to new formats. Outcome is the actual database with its data

38. 10/17/2000Database Management -- R. Larson Database Implementation DA & DBA functions Specify database access policies (DA & DBA) Establish Security controls (DBA) Supervise Database loading (DBA) Specify test procedures (DBA) Develop application programming standards (DBA) Establish procedures for backup and recovery (DBA) Conduct User training (DA & DBA)

39. 10/17/2000Database Management -- R. Larson Operation and Maintenance 1: Operations Users are responsible for updating the database, DA and DBA are responsible for developing procedures that ensure the integrity and security of the database during the update process. Specific responsibility for data collection, editing and verification must be assigned Quality assurance must be practiced to protect and audit the database quality.

40. 10/17/2000Database Management -- R. Larson Operation and Maintenance 2: Maintenance The ongoing process of updating the database to keep it current –adding new records –deleting obsolete records –changing data values in particular records –modifying relation structures (e.g. adding new fields) Privacy, security, access control must be in place. Recovery and Backup procedures must be established and used

41. 10/17/2000Database Management -- R. Larson Operation and Maintenance: DA & DBA functions Monitor database performance (DBA) Tune and reorganize databases (DBA) Enforce standards and procedures (DBA) Support users (DA & DBA)

42. 10/17/2000Database Management -- R. Larson Growth & Change Change is a way of life –Applications, data requirements, reports, etc. will all change as new needs and requirements are found –The Database and applications and will need to be modified to meet the needs of changes to the organization and the environment. –Database performance should be monitored to maintain a high level of system performance.

43. 10/17/2000Database Management -- R. Larson Growth & Change: DA & DBA functions Implement change control procedures (DA & DBA) Plan for growth and change (DA & DBA) Evaluate new technology (DA & DBA)

44. 10/17/2000Database Management -- R. Larson Issues/functions in Database Administration Planning and Design (we have already looked at theses processes in detail) Data Integrity Backup and Recovery Security Management

45. 10/17/2000Database Management -- R. Larson Data Integrity Intrarecord integrity (enforcing constraints on contents of fields, etc.) Referential Integrity (enforcing the validity of references between records in the database) Concurrency control (ensuring the validity of database updates in a shared multiuser environment).

46. 10/17/2000Database Management -- R. Larson No Concurrency Control: Lost updates Read account balance (balance = $1000) Withdraw $200 (balance = $800) Write account balance (balance = $800) Read account balance (balance = $1000) Withdraw $300 (balance = $700) Write account balance (balance = $700) John Marsha ERROR!

47. 10/17/2000Database Management -- R. Larson Concurrency Control: Locking Locking levels –Database –Table –Block or page –Record –Field Types –Shared (S locks) –Exclusive (X locks)

48. 10/17/2000Database Management -- R. Larson Concurrency Control: Updates with X locking Lock account balance Read account balance (balance = $1000) Withdraw $200 (balance = $800) Write account balance (balance = $800) Unlock account balance Read account balance (DENIED) Lock account balance Read account balance (balance = $800) etc... John Marsha

49. 10/17/2000Database Management -- R. Larson Concurrency Control: Deadlocks Place S lock Read account balance (balance = $1000) Request X lock (denied) wait... Place S lock Read account balance (balance = $1000) Request X lock (denied) wait... John Marsha Deadlock!

50. 10/17/2000Database Management -- R. Larson Concurrency Control Avoiding deadlocks by maintaining tables of potential deadlocks and “backing out” one side of a conflicting transaction.

51. 10/17/2000Database Management -- R. Larson Database Security Views or restricted subschemas Authorization rules to identify users and the actions they can perform User-defined procedures (and rule systems) to define additional constraints or limitations in using the database Encryption to encode sensitive data Authentication schemes to positively identify a person attempting to gain access to the database

52. 10/17/2000Database Management -- R. Larson Views A subset of the database presented to some set of users. –SQL: CREATE VIEW viewname AS SELECT field1, field2, field3,…, FROM table1, table2 WHERE ; –Note: “queries” in Access function as views.

53. 10/17/2000Database Management -- R. Larson Authorization Rules Most current DBMS permit the DBA to define “access permissions” on a table by table basis (at least) using the GRANT and REVOKE SQL commands. Some systems permit finer grained authorization (most use GRANT and REVOKE on variant views.

54. 10/17/2000Database Management -- R. Larson Database Backup and Recovery Backup Journaling (audit trail) Checkpoint facility Recovery manager