RDBMS - Advance 2101. What are the four objectives of the selection of a data type?
Ans: A data type should be selected so that all possible values are represented using minimal storage space. The data type should help to ensure data integrity and support all possible data manipulations (i.e., cannot place a letter in a field such as salary where a number is required).
102. Describe the four types of indexes.
Ans: A unique primary index is unique and is used to find and store a row. A nonunique primary index is not unique and is used to find a row but also where to store a row (based on its unique primary index). A unique secondary index is unique for each row and used to find table rows. A nonunique secondary index is not unique and used to find table rows.
103. What is denormalization and why would someone consider doing so?
Ans: Denormalization is the process of taking normalized relations and changing them so that they are not longer normalized. This process may lead to anomalies and create data redundancy as negative consequences. However, the revised relations should improve database performance.
104. Compare a hierarchical and network database model?
Ans: The hierarchical model is a top-down structure where each parent may have many children but each child can have only one parent. This model supports one-to-one and one-to-many relationships. The network model can be much more flexible than the hierarchical model since each parent can have multiple children but each child can also have multiple parents. This model supports one-to-one, one-to-many, and many-to-many relationships.
105. Describe the differences between vertical and horizontal portioning.
Ans: Horizontal portioning is where the rows in a relation are separated by some criteria and placed into a new relation or file with the same layout as the original relation (in this case only the records in each file differ). Vertical portioning is where the columns in a relation are separated by some criteria and placed into a new relation or file with a different layout as the original relation.
If you have some tips/suggestion please mail me @ Anshul24mehta@gmail.com.
106. Explain the difference between a dynamic and materialized view.
Ans: A dynamic view may be created every time that a specific view is requested by a user. A materialized view is created and or updated infrequently and it must be synchronized with its associated base table(s).
107. Discuss some of the techniques that can be used to tune operational performance.
Ans: Choosing primary and secondary keys can increase the speed of row selection, joining, and row ordering. Selecting the appropriate file organization for base tables and indexes can also improve performance. Clustering related rows together and maintaining statistics about tables and indexes can lead to increased efficiency.
108. Briefly describe the three types of SQL commands.
Ans: Data definition language commands are used to create, alter, and drop tables. Data manipulation commands are used to insert, modify, update, and query data in the database. Data control language commands help the DBA to control the database.
109. What are the steps to follow when preparing to create a table?
Ans:
1. Identify the data type, length, and precision for each attribute.
2. Identify the columns that can accept a null value.
3. Identify the columns that need to be unique.
4. Identify primary and related foreign keys with the parent table being created before the child.
5. Determine default values.
6. Determine where the domain values are that need to be constrained.
7. Create the indexes.
110. What are some disadvantages of a standard language such as SQL?
Ans: A standard language can hinder the effort to create a new language. One standard is never enough to meet all of the business needs. A standard can be a compromise among interested parties which can cause the standard to not be ideal. If a standard is altered by some, than portability between platforms could be hurt.
If you have some tips/suggestion please mail me @ Anshul24mehta@gmail.com.
111. Explain a join between tables
Ans: A join allows tables to be linked to other tables when a relationship between the tables exists. The relationships are established by using a common column in the tables and often uses the primary/foreign key relationship.
112. Describe and contrast a trigger and a procedure.
Ans: Triggers are stored and controlled in the DBMS. A trigger is executed automatically when a condition is met (INSERT, UPDATE, or DELETE). A procedure is also stored in a database. A procedure is not executed automatically.
113. Briefly describe an outer join.
Ans: An outer join includes the records that match and those that do not have a matching value in another table. Outer joins can be a LEFT outer join (includes all records from the first table listed) or a RIGHT outer join (includes all records from the second table listed). Outer joins are not easily used with more than two tables.
114. Describe a subquery.
Ans: A subquery is a query that is composed of two queries. The first query (inner query) is within the WHERE clause of the other query (outer query). In some cases the inner query provides results for the outer query to process. In other cases, the outer query results provide results for the inner query (correlated subquery).
115. Describe the difference between embedded and dynamic SQL.
Ans: Embedded SQL is the process of including hard coded SQL statements. These statements do not change unless the source code is modified. Dynamic SQL is the process of generating SQL on the fly. The statements generated do not have to be the same each time.
If you have some tips/suggestion please mail me @ Anshul24mehta@gmail.com.
116. Explain the difference between two and three-tier architectures.
Ans: A three-tier architecture includes a client and two server layers. The application code is stored on the application server and the database is stored on the database server. A two-tier architecture includes a client and one server layer. The database is stored on the database server.
117. Describe and contrast SQL and QBE.
Ans: QBE is a direct-manipulation database language that uses a graphical approach to query construction. Some database systems translate QBE queries into SQL. QBE does not adhere to a standard but SQL does. Both SQL and QBE are relational database languages.
118. Describe ODBC
Ans: ODBC is a standard that contains an interface that provides a common language for application programs to access and process SQL databases. In order to use ODBC, a driver, server name, database name, user id, and password are required. ODBC is important for Internet applications and has gained wide acceptance.
119. Compare a thin and a fat client.
Ans: A fat client is a PC that is responsible where most processing occurs on the client rather than the server. Some of the fat client activities include processing, presentation logic, and business rules logic. A thin client is a PC where only limited processing occurs. In these cases, more processing should occur on the application server.
120. Describe some reasons that someone familiar with Microsoft Access will want to learn VBA.
Ans: You can perform more complex functions and error handling can be accommodated by VBA. VBA code will execute faster since code runs faster than macros and maintenance is easier because VBA modules are stored with the forms and reports. Reading VBA is easier because you can see the entire code. Finally, you can pass parameters and use OLE automation better.
If you have some tips/suggestion please mail me @ Anshul24mehta@gmail.com.
121. Describe middleware applications that ease the connection of databases to Web applications.
Ans: Both ASP and ColdFusion are middleware that ease the connection of databases to Web applications. Both require the use of several files. Both use tags and are executed on the server. Both Internet Explorer and Netscape can access these files. The programmer does not need to be concerned with the client when they work with this middleware.
122. Describe JavaScript and VBScript.
Ans: JavaScript shares many features with Java. Developers use it to achieve interactivity. JavaScript is an open language and does not require a license. It is supported by both Internet Explorer and Netscape. VBScript is similar to JavaScript. It is based on Visual Basic but is simpler. Microsoft developed this language.
123. Describe Web Services.
Ans: Web Services are improving the ability of computers to communicate over the Internet. These services use XML programs and usually run in the background. Easier integration of applications may be possible because developers do not need to be familiar with the technical details with applications that are being integrated. UDDI is a technical specification for creating a distributed registry of Web services and businesses that are open to communicating through Web services.
124. Provide an overview of XML.
Ans: XML is used to structure and manipulate data involved with a browser and is becoming the standard for e-commerce. XML uses tags that are similar to HTML in that they use the angle brackets, but XML describes the content whereas HTML describes the appearance. The XML schema standard was published in May 2001 by W3C.
125. Describe Website security issues.
Ans: Website security issues include unauthorized access to the several aspects of one's Website. Security measures should include all aspects of the system such as the network, operating level, database, and Web server. Regular monitoring and security testing by a company should help to avoid intrusion into one's system.
If you have some tips/suggestion please mail me @ Anshul24mehta@gmail.com.
126. Explain the role of metadata for the three-layer architecture.
Ans: Each of the three layers has a metadata layer linked with it. The metadata layer describes the properties or characteristics of the data. The operational metadata describe the data used in the various operational and external systems. The enterprise data warehouse metadata describe the reconciled data layer. The data mart metadata describes the derived data layer.
127. Describe why operational and informational systems are separate.
Ans: Operational systems are used to run the business in real time on a daily basis and contain current data. Non-managers and non-analysts work in this type of system. Operational systems must process large volumes of data. Informational systems are used to support decisions and contain historical data. Managers and analysts work in this type of system. Informational systems have periodic batch updates.
128. Describe a data warehouse.
Ans: A data warehouse is organized around specific subjects. The data is defined using consistent naming, format, and encoding structure standards. The data contains a time element, so that the data can be studied for trends. No data in a data warehouse can be updated by end users.
129. Explain why an information gap exists in most organizations.
Ans: One reason that an information gap exists is the fact that systems have been developed in separate, segmented efforts. This has helped the data from being stored in an integrated database and thus the data is in an inconsistent structure. The other reason for the gap is that most systems are created to support the operational aspect of an organization. The systems were not developed for decision making.
130. Describe the differences between a data warehouse and data mart.
Ans: A data warehouse is for the enterprise and contains multiple subjects. A data mart is for a specific functional area and focuses on one subject. A data warehouse is flexible and data-oriented and contains detailed historical data. A data mart is restrictive and project-oriented and contains some historical data.
If you have some tips/suggestion please mail me @ Anshul24mehta@gmail.com.
131. Describe the difference between data and database administration.
Ans: Data administration is responsible for the overall management of data resources. Some of the core roles include the creation of data polices, procedures and standards, resolve data ownership issues, and manage the information repository. Database administration is physical database oversight. Some of the core duties include the selection of the DBMS and software tools, the installation and upgrade of the DBMS, and database performance tuning.
132. What are some of the important security features of a DBMS?
One of the features includes the use of views which allows the presentation of only data needed by someone and limits the capability of database updates. The use of integrity controls includes such things as domains, assertions, and checks. Also authorization rules, user-defined procedures, encryption, authentication schemes, and backups are important.
133. Describe concurrency control.
Ans: Concurrency control is the process managing simultaneous operations against a database so that database integrity is not compromised. There are two approaches to concurrency control. The pessimistic approach involves locking and the optimistic approach involves versioning.
134. Explain locking.
Ans: Locking is denying others the ability to update a record until someone completes the update or releases the record. Locking can occur on many different levels in a database. It can occur at the database, table, record, or field level. A lock can be shared (another can read the record while an update is in progress) or exclusive (no one can read the record while an update is in progress).
135. Explain issues for database performance.
Ans: The installation of the database is an important issue since the better the installation, the better the performance could be. Memory usage is learning how the DBMS uses main memory and then using that knowledge to enable better performance. I/O is usually very intense in a DB, so understanding how users will use the data will help to prepare the database better. CPU usage and application tuning are also important considerations.
If you have some tips/suggestion please mail me @ Anshul24mehta@gmail.com.
136. Describe the difference between homogeneous and heterogeneous distributed database.
Ans: A homogenous database is one that uses the same DBMS at each node. Either each node can work independently or a central DBMS may coordinate database activities. A heterogeneous database is one that may have a different DBMS at each node. It may support some or all of the functionality of one logical database. It may support full Distributed DBMS functionality or partial Distributed DBMS functionality.
137. What is a distributed database?
Ans: A distributed database is a single logical database that is spread across more than one node or locations that are all connected via some communication link. It requires multiple DBMSs, running at each remote site. A distributed database can be either homogenous (same DBMS at each node) or heterogeneous (different DBMS at some nodes).
138. What is the difference between horizontal and vertical partitioning?
Ans: Horizontal partitioning is where some rows of a table are placed into the base relations at one site and other rows are placed at another site. Vertical partitioning is where some columns of a table are placed into the base relations at one site and other columns are placed at another site but each all of these relations must share a common domain.
139. Explain concurrency transparency.
Ans: Concurrency transparency is where each transaction in a distributed database is treated as if it is the only one in the system. Therefore if several transactions are running at one time, the results will be the same as if each transaction was run in serial order. The transaction manager helps to provide concurrency control. The three methods that may be used are locking, versioning, and timestamping.
140. Explain snapshot replication.
Ans: Snapshot replication can be used when an application does not require that the data always be current. These applications can be updated by periodic table copying or snapshots. As part of the snapshot effort, all of the data to be included in the snapshot is collected at a primary point. Then a read-only snapshot is taken and the snapshot is sent to each site so that the update can be made.
Click on more advance RDBMS reading -> RDBMS - Advance 1 and RDBMS - Advance 2
You can revise the basic here : RDBMS - BASIC 1 and RDBMS - BASIC 2