Lecture Handout. Database Management System. Overview of Lecture. Vertical Partitioning. Lecture No. 24

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1 Lecture Handut Database Management System Lecture N. 24 Reading Material Database Systems Principles, Design and Implementatin written by Catherine Ricard, Maxwell Macmillan. Database Management Systems, 2 nd editin, Raghu Ramakrishnan, Jhannes Gehrke, McGraw-Hill Overview f Lecture Vertical Partitining Replicatin Structured Query Language (SQL) In the previus lecture we were discussing physical data base design, in which we studied denrmalizatin and its different aspects. We als studied the hrizntal partitining. In this lecture we will study vertical partitining. Vertical Partitining Vertical partitining is dne n the basis f attributes. Same table is split int different physical recrds depending n the nature f accesses. Primary key is repeated in all vertical partitins f a table t get the riginal table. In cntrast t hrizntal partitining, vertical partitining lets yu restrict which clumns yu send t ther destinatins, s yu can replicate a limited subset f a table's clumns t ther machines. We will nw see it with the example f a student relatin as under: - Cpyright Virtual University f Pakistan Page 188 PDF Creatr: PDF4U Pr DEMO Versin. If yu want t remve this line, please purchase the full versin

2 STD (stid, sname, sadr, sphne, cgpa, prname, schl, mtmrks, mtsubs, clgname, intmarks, intsubs, dclg, bmarks, bsubs) Nw in this relatin the student relatin has number f attributes. It is in 3NF. But the nature f accesses in this relatin is different. S nw we will partitin this relatin vertically as under. STD (stid, sname, sadr, sphne, cgpa, prname) STDACD (sid, schl, mtmrks, mtsubs, clgname, intmarks, intsubs, dclg, bmarks, bsubs) The prcess f cpying a prtin f the database frm ne envirnment t anther and keeping subsequent cpies f the data in synchrnizatin with the riginal surce Changes made t the riginal surce are prpagated t the cpies f the data in ther envirnments. It is the final frm f denrmalizatin. It increases the access speed and failure damage f the database. In replicatin entire table r part f table can be replicated. Replicatin is nrmally adpted in thse applicatins, where updatin is nt very frequent, because if updatin is frequent s then it will have prblems f updatin in all the cpies f database relatins. This will als slw dwn the speed f database. Clustering Files Clustering is a prcess, which means t place recrds frm different tables t place in adjacent physical lcatins, called clusters. It increases the efficiency since related recrds are placed clse t each ther. Clustering is als suitable t relatively static situatins. The advantage f clustering is that while accessing the recrds it is easy t access. Define cluster, define the key f the cluster, and include the tables int the cluster while creating assciating the key with it. Summary f Physical Database Design Database design is the prcess f transfrming a lgical data mdel int an actual physical database. A lgical data mdel is required befre yu can even begin t design a physical database. The first step is t create an initial physical data mdel by transfrming the lgical data mdel int a physical implementatin based n an understanding f the DBMS t be used fr deplyment. T successfully create a physical database design yu will need t have a gd wrking knwledge f the features f the DBMS including: Cpyright Virtual University f Pakistan Page 189 PDF Creatr: PDF4U Pr DEMO Versin. If yu want t remve this line, please purchase the full versin

3 In-depth knwledge f the database bjects supprted by the DBMS and the physical structures and files required t supprt thse bjects. Details regarding the manner in which the DBMS supprts indexing, referential integrity, cnstraints, data types, and ther features that augment the functinality f database bjects. Detailed knwledge f new and bslete features fr particular versins r releases f the DBMS t be used. Knwledge f the DBMS cnfiguratin parameters that are in place. Data definitin language (DDL) skills t translate the physical design int actual database bjects. Armed with the crrect infrmatin, yu can create an effective and efficient database frm a lgical data mdel. The first step in transfrming a lgical data mdel int a physical mdel is t perfrm a simple translatin frm lgical terms t physical bjects. Of curse, this simple transfrmatin will nt result in a cmplete and crrect physical database design it is simply the first step. The transfrmatin cnsists f the fllwing things: Transfrming entities int tables Transfrming attributes int clumns Transfrming dmains int data types and cnstraints There are many decisins that must be made during the transitin frm lgical t physical. Fr example, each f the fllwing must be addressed: The nullability f each clumn in each table Fr character clumns, shuld fixed length r variable length be used Shuld the DBMS be used t assign values t sequences r identity clumns? Implementing lgical relatinships by assigning referential cnstraints Building indexes n clumns t imprve query perfrmance Chsing the type f index t create: b-tree, bit map, reverse key, hash, partitining, etc. Cpyright Virtual University f Pakistan Page 190 PDF Creatr: PDF4U Pr DEMO Versin. If yu want t remve this line, please purchase the full versin

4 Deciding n the clustering sequence fr the data Other physical aspects such as clumn rdering, buffer pl specificatin, data files, denrmalizatin, and s n. Structured Query Language SQL is an ANSI standard cmputer language fr accessing and manipulating databases. SQL is standardized, and the current versin is referred t as SQL-92. Any SQLcmpliant database shuld cnfrm t the standards f SQL at the time. If nt, they shuld state which flavr f SQL (SQL-89 fr example) s that yu can quickly figure ut what features are and are nt available. The standardizatin f SQL makes it an excellent tl fr use in Web site design. Mst Web applicatin develpment tlkits, mst ntably Allaire's Cld Fusin and Micrsft's Visual InterDev, rely n SQL r SQL-like statements t cnnect t and extract infrmatin frm databases. A slid fundatin in SQL makes hking databases t Web sites all the simpler. SQL is used t cmmunicate with a database. Accrding t ANSI (American Natinal Standards Institute), it is the standard language fr relatinal database management systems. SQL statements are used t perfrm tasks such as update data n a database, r retrieve data frm a database. Sme cmmn relatinal database management systems that use SQL are: Oracle, Sybase, Micrsft SQL Server, Access, Ingres, etc. Althugh mst database systems use SQL, mst f them als have their wn additinal prprietary extensins that are usually nly used n their system. Hwever, the standard SQL cmmands such as "Select", "Insert", "Update", "Delete", "Create", and "Drp" can be used t accmplish almst everything that ne needs t d with a database. This tutrial will prvide yu with the instructin n the basics f each f these cmmands as well as allw yu t put them t practice using the SQL Interpreter. Benefits f Standard SQL: Fllwing are the majr benefits f SQL:- Reduced training cst Applicatin prtability Applicatin lngevity Reduced dependence n a single vendr Cpyright Virtual University f Pakistan Page 191 PDF Creatr: PDF4U Pr DEMO Versin. If yu want t remve this line, please purchase the full versin

5 Crss-system cmmunicatinsql is used fr any type f interactin with the database thrugh DBMS. It can be used fr creating tables, insertin in the table and deletin as we well and ther peratins als. The DBMS fr ur curse is Micrsft s SQL Server 2000 desktp editin. There are tw main tls Query Analyzer and Enterprise Manager; bth can be used. Fr SQL practice we will use Query Analyzer. S yu must use this sftware fr the SQL queries. S we will be using this sftware fr ur SQL queries. Summary: In this lecture we have studied the vertical partitining, its imprtance and methds f applying. We have als studied replicatin and clustering issues. We then started with the basics f SQL and in the next lectures we will use SQL Server fr the queries. Exercise: Critically examine the tables drawn fr Examinatin system and see if there is a requirement f vertical partitining and then carry ut the prcess. Als install the SQL Server and acquaint yurself with this sftware. Cpyright Virtual University f Pakistan Page 192 PDF Creatr: PDF4U Pr DEMO Versin. If yu want t remve this line, please purchase the full versin

Lecture Handout. Database Management System. Overview of Lecture. Inheritance Is. Lecture No. 11. Reading Material

Lecture Handout. Database Management System. Overview of Lecture. Inheritance Is. Lecture No. 11. Reading Material Lecture Handut Database Management System Lecture N. 11 Reading Material Database Systems Principles, Design and Implementatin written by Catherine Ricard, Maxwell Macmillan. Overview f Lecture Inheritance