VIVA VOICE QUESTIONS AND ANSWERS. 1. What is database? A database is a logically coherent collection of data with some inherent meaning, representing. dbms viva questions and answers for lab - dbms viva questions and answers dr. another table having similar kind dbms lab viva questions and answers pdf. DBMS Viva Questions MCA Idol - Free download as PDF File .pdf), Text File .txt) DBMS Basic VIVA Questions and Answers .. Viva Questions for Java Lab.
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DBMS LAB VIVA Questions and Answers pdf free download for cse,DBMS LAB VIVA Questions with Answers,interview ronaldweinland.info,online. ronaldweinland.info DBMS VIVA QUESTIONS 1. What is database? A database is a logically coherent . A database language may also incorporate features like: DBMS-specific Configuration and management of storage engine. Computations to modification of.
Thus the given FDs is in 1NF. A dominant entity is the entity a on the N side in a 1 : N relationship b on the 1 side in a 1 : N relationship c on either side in a 1 : 1 relationship d nothing to do with 1 : 1 or 1 : N relationship What is Storage Manager? It is a program module that provides the interface between the low-level data stored in database, application programs and queries submitted to the system. What is Buffer Manager? It is a program module, which is responsible for fetching data from disk storage into main memory and deciding what data to be cache in memory.
You are not liable to change any computed value in any particular view. Full-text index definitions cannot be applied. Temporary views cannot be created. Temporary tables cannot contain views. A 'correlated subquery' is a sort of sub query but correlated subquery is reliant on another query for a value that is returned. In case of execution, the sub query is executed first and then the correlated query. Storage and access of data from the central location in order to take some strategic decision is called Data Warehousing.
Enterprise management is used for managing the information whose framework is known as Data Warehousing. Joins help in explaining the relation between different tables. They also enable you to select data with relation to data in another table. Blank rows are left at the specified side by joining tables in other side.
Indexes help in improving the speed as well as the query performance of database. The procedure of boosting the collection of indexes is named as Index hunting. Index hunting helps in improving the speed as well as the query performance of database. The followed measures are achieved to do that: The query optimizer is used to coordinate the study of queries with the workload and the best use of queries suggested based on this.
Index, query distribution along with their performance is observed to check the effect. Tuning databases to a small collection of problem queries is also recommended. The disadvantages of query are: No indexes Stored procedures are excessively compiled.
Complicated joins making up inadequately written query.
Cursors and temporary tables showcase a bad presentation. Ways to efficiently code transactions: User input should not be allowed while transactions.
While browsing, transactions must not be opened of data. Transactions must be kept as small as possible. Lower transaction segregation levels.
Least information of data must be accessed while transacting.
Executive plan can be defined as: SQL Server caches collected procedure or the plan of query execution and used thereafter by subsequent calls. An important feature in relation to performance enhancement. Data execution plan can be viewed textually or graphically. A data structure in the form of tree which stores sorted data and searches, insertions, sequential access and deletions are allowed in logarithmic time. Iterating over all the table rows is called Table Scan while iterating over all the index items is defined as Index Scan.
Such an entity set is termed a Strong entity set. What is Specialization The process of designating sub groupings within an entity set is called specialization.
For example, customer entities may be described further by the attribute customer-id, whereas employee entities may be described further by the attributes employee-id and salary. What is Aggregation Aggregation represents abstract entities by allowing relationship between relationships. As you work with ER Diagrams you will come across the need for certain type of entities that are overlapping. For example, an Employee workson a branch. An Employee manages some tasks.
The Works-on entity here can be abstracted via the use of aggregation. This is represented in a ER diagram by a diamond shape. How to Create Table? The operation cannot be rolled back and no triggers will be fired. The DROP command removes a table from the database. All the tables rows, indexes and privileges will also be removed. No DML triggers will be fired. The operation cannot be rolled back. What is View? A view is a virtual table in the database whose contents are defined by a query.
Advantages of VIEW? Security, Query simplicity, Structural simplicity, Insulation from change, Data integrity Disadvantages of VIEW? Performance issue, Update restrictions What are different DDL commands?
Create, drop, and alter Select, insert, update, delete What is Joins? The process of forming pairs of rows by matching the contents of related columns is called joining the tables. What is trigger The concept of a trigger is relatively straightforward.
For any event that causes a change in the contents of a table, a user can specify an associated action that the DBMS should carry out. What are the different types of storage? Primary storage: This category includes storage media that can be operated on directly by the computer central processing unit CPU , such as the computer main memory and smaller but faster cache memories. Secondary storage: This category includes magnetic disks, optical disks, and tapes.
These devices usually have a larger capacity, cost less, and provide slower access to data than do primary storage devices. What is indexing? A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of slower writes and increased storage space.
Indices can be created using one or more columns of a database table, providing the basis for both rapid random lookups and efficient access of ordered records. What is Tree Structured Indexing?
The data entries are arranged in sorted order by search key value, and a hierarchical search data structure is maintained that directs searches to the correct page of data entries. What is Hash Based indexing? We can organize records using a technique called hashing to quickly find records that have a given search key value. For example, if the file of employee records is hashed on the name field, we can retrieve all records about Joe.
In this approach, the records in a file are grouped in buckets, where a bucket consists of a primary page and, possibly, additional pages linked in a chain. The bucket to which a record belongs can be determined by. On inserts, the record is inserted into the appropriate bucket, with overflow pages allocated as necessary.
What is Functional dependency? Functional dependency describes the relationship between attributes in a relation. A and B may each consist of one or more attributes. Normalization is the process of successively reducing relations with anomalies to produce smaller and well structured relations. First normal form 1NF is a relation that has a primary key and in which there are no repeating groups. Second normal form 2NF a relation in first normal form in which every non key attribute is fully functionally dependent on the primary key.
Third normal form 3NF a relation that is in second normal form and has no transitive dependencies. It is a slightly stronger version of the third normal form 3NF. A table is in Boyce-Codd normal form if and only if for every one of its non-trivial [dependencies] X Y, X is a superkeythat is, X is either a candidate key or a superset thereof. It is thought that a table is in 3NF if and only if 1 the table is in second normal form or 2NF, which is a first normal code, or 1NF, that has met the criteria to become a 2NF , and 2 every non-prime attribute of the table is non-transitively dependent on every key of the table meaning it is not directly dependent on every key.
What is Transaction? A transaction is a collection of operations that performs a single logical function in a database application What is Recovery? What are its techniques?
Process of restoring database to a correct state in the event of a failure. The Recovery techniques are as follows: Deferred Update Updates are not written to the database until after a transaction has reached its commit point. Immediate Update Updates are applied to database as they occur. Need to redo updates of committed transactions following a failure. Shadow Paging. Maintain two page tables during life of a transaction: When transaction starts, two pages are the same.
Shadow page table is never changed thereafter and is used to restore database in event of failure. What is locking? Explain locking techniques. A shared lock is used by the DBMS when a transaction wants to read data from the database. Another concurrent transaction can also acquire a shared lock on the same data, allowing the other transaction to also read the data.
An exclusive lock is used by the DBMS when a transaction wants to update data in the database. When a transaction has an exclusive lock on some data, other transactions cannot acquire any type of lock shared or exclusive on the data. What is deadlock?
A deadlock is a situation wherein two or more competing actions are each waiting for the other to finish, and thus neither ever does. What is two phase locking? According to the two-phase locking protocol, a transaction handles its locks in two distinct, consecutive phases during the transaction's execution: Expanding phase number of locks can only increase: Shrinking phase: Normally the GRANT statement is used by owner of the table or view to give other users access to the data.
The GRANT statement includes list of the privileges to be granted, name of the table to which privileges apply and user id to which privileges are granted.
What is Serializability? In concurrency control of databases, transaction processing transaction management , and various transactional applications, both centralized and distributed, a transaction schedule is serializable, has the Serializability property, if its outcome the resulting database state, the values of the database's data is equal to the outcome of its transactions executed serially, i.
What are Locking parameters? Lock size, Number of locks, Lock timeout Database level locking: Locking can be implemented at various levels of the Database. In its crudest form, the DBMS could lock the entire database for each transaction. Page level locking: Many DBMS products implement locking at the page level.
In this scheme, the DBMS locks individual blocks of data "pages" from the disk as they are accessed by a transaction. Row level locking: Over the last several years, most of the major commercial DBMS systems have moved beyond page-level locking to row-level locks.
What is Authorization and Integrity manager? It is the program module, which tests for the satisfaction of integrity constraint and checks the authority of user to access data. What are stand-alone procedures? Procedures that are not part of a package are known as stand-alone because they independently defined. These types of procedures are not available for reference from other Oracle tools. Another limitation of stand-alone procedures is that they are compiled at run time, which slows execution.
What are cursors give different types of cursors? The language supports the use two types of cursors 1. Implicit 2. What are stored-procedures? And what are the advantages of using them? Stored procedures are database objects that perform a user defined operation. A stored procedure can have a set of compound SQL statements. A stored procedure executes the SQL commands and returns the result to the client.
Stored procedures are used to reduce network traffic. What is a query? A query with respect to DBMS relates to user commands that are used to interact with a data base. The query language can be classified into data definition language and data manipulation language. What do you mean by Correlated subquery?
Subqueries, or nested queries, are used to bring back a set of rows to be used by the parent query. Depending on how the subquery is written, it can be executed once for the parent query or it can be executed once for each row returned by the parent query.
If the subquery is executed for each row of the parent, this is called a correlated subquery. A correlated subquery can be easily identified if it contains any references to the parent subquery columns in its WHERE clause.
Columns from the subquery cannot be referenced anywhere else in the parent query. The following example demonstrates a non-correlated subquery. CNUM What is meant by query optimization? The phase that identifies an efficient execution plan for evaluating a query that has the least estimated cost is referred to as query optimization. What is durability in DBMS? Once the DBMS informs the user that a transaction has successfully completed, its effects should persist even if the system crashes before all its changes are reflected on disk.
This property is called durability. What do you mean by atomicity and aggregation? Either all actions are carried out or none are. Users should not have to worry about the effect of incomplete transactions. DBMS ensures this by undoing the actions of incomplete transactions. A concept which is used to model a relationship between a collection of entities and relationships. It is used when we need to express a relationship among relationships.
What is a Phantom Deadlock? In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to identify deadlocks that do not really exist.
Such situations are called phantom deadlocks and they lead to unnecessary aborts.
What is a checkpoint and When does it occur? By taking checkpoints, the DBMS can reduce the amount of work to be done during restart in the event of subsequent crashes.
What are the different phases of transaction? Different phases are 1. Analysis phase, 2.