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Showing posts with the label DBMS

Normalization

Normalization is the process of splitting relations into well-structured relations that allow users to insert, delete, and update tuples without introducing database inconsistencies. The focus of normalization is to reduce redundant data to the minimum.  Normalization is also called “Bottom-up approach”, because this technique requires very minute details like every participating attribute and how it is dependant on the key attributes, is crucial. If you add new attributes after normalization, it may change the normal form itself. Through Normalization, the collection of data in a single table is distributed into multiple tables with specific relation. Without normalization many problems can occur when trying to load an integrated conceptual model into the DBMS. These problems arise from relations that are generated directly from user views are called anomalies. There are three types of anomalies: RollNo StudentName CourseNo CourseName Instructor 120 SKL CS-7

Advantages of DBMS over Conventional File System

The principal advantages of DBMS over file processing system: • Flexibility : Because programs and data are independent, programs do not have to be modified when types of unrelated data are added to or deleted from the database, or when physical storage changes. • Fast response to information requests : Because data is integrated into a single database, complex requests can be handled much more rapidly than locating data separately. In many businesses, faster response means better customer service. • Multiple access : Database software allows data to be accessed in a variety of ways (through various key fields), by using several programming languages (both3GL and nonprocedural4GL programs). • Lower user training costs : Users often find it easier to learn such systems and training costs may be reduced. Also, the total time taken to process requests may be less, which would increase user productivity. • Less storage : Theoretically, all occurrences of data items need be stored only on

MCQ on Oracle

1. What does a COMMIT statement do to a CURSOR a] Open the Cursor b] Fetch the Cursor c] Close the Cursor d] None of the above   2. Which of the following is TRUE 1] Host variables are declared anywhere in the program 2] Host variables are declared in the DECLARE section a] Only 1 is TRUE b] Only 2 is TRUE c] Both 1 & 2are TRUE d] Both are FALSE   3. Which of the following is NOT VALID is PL/SQL a] Bool boolean; b] NUM1, NUM2 number; c] deptname dept.dname%type; d] date1 date := sysdate   4. Declare fvar number := null; svar number := 5 Begin goto << fproc>> if fvar is null then << fproc>> svar := svar + 5 end if; End; What will be the value of svar after the execution ? a] Error b] 10 c] 5 d] None of the above   5. Which of the following is not correct about an Exception ? a] Raised automatically / Explicitly in response to an ORACLE_ERROR b] An exception will be raised when an error occurs in that block c] Process terminates after completion of error seque