Datastructures(1)

1. What is data structure?

·          A data structure is a way of organizing data that considers not only the items stored, but also their relationship to each other.

·          Advance knowledge about the relationship between data items allows designing of efficient algorithms for the manipulation of data.

2. List out the areas in which data structures are applied extensively?

1.     Compiler Design,

2.     Operating System,

3.     Database Management System,

4.     Statistical analysis package,

5.     Numerical Analysis,

6.     Graphics,

7.     Artificial Intelligence,

8.     Simulation

3. What are the major data structures used in the following areas : RDBMS, Network data model and Hierarchical data model.

1.     RDBMS = Array (i.e. Array of structures)

2.     Network data model = Graph

3.     Hierarchical data model = Trees

4. if you are using C language to implement the heterogeneous linked list, what pointer type will you use?

·          The heterogeneous linked list contains different data types in its nodes and we need a link, pointer to connect them.

·          It is not possible to use ordinary pointers for this. So we go for void pointer.

·          Void pointer is capable of storing pointer to any type as it is a generic pointer type.

5. Minimum number of queues needed to implement the priority queue?

Two. One queue is used for actual storing of data and another for storing priorities.

6. What is the data structures used to perform recursion?

Stack. Because of its LIFO (Last in First Out) property it remembers its 'caller' so knows whom to return when the function has to return. Recursion makes use of system stack for storing the return addresses of the function calls.

Every recursive function has its equivalent iterative (non-recursive) function. Even when such equivalent iterative procedures are written, explicit stack is to be used.

7. What are the notations used in Evaluation of Arithmetic Expressions using prefix and postfix forms?

Polish and Reverse Polish notations.

8. Convert the expression ((A + B) * C - (D - E) ^ (F + G)) to equivalent Prefix and Postfix notations.

1.     Prefix Notation: ^ - * +ABC - DE + FG

2.     Postfix Notation: AB + C * DE - - FG + ^

9. Sorting is not possible by using which of the following methods? (Insertion, Selection, Exchange, Deletion)

Sorting is not possible in Deletion. Using insertion we can perform insertion sort, using selection we can perform selection sort, using exchange we can perform the bubble sort (and other similar sorting methods). But no sorting method can be done just using deletion.

10. What are the methods available in storing sequential files ?

1.     Straight merging,

2.     Natural merging,

3.     Polyphase sort,

4.     Distribution of Initial runs.

TESTING - The W-Model of Testing

- Introduced by Paul Herzlich in 1993.

- Attempts to address shortcomings in V-model.

- Rather than focus on specific dynamic test stages (V-Model), W-Model focuses on the development product themselves.

- Everyday development activity that produces a work product is “showed” by the test activity.

- Purpose to test whether the objectives of the development activity has been met and deliverables meets its requirements.

- W-Model focuses specifically on the product risks of concern at the point where testing can be most effective.

W-Model and Static Test Techiniques:

- There is wide range of techniques available for the products of the left hand side.

W-Model and Dynamic test technique:

Relational Data Base Management Systems (RDBMS)(4)

1.       What are different Types of Join?

1. Cross Join A cross join that does not have a WHERE clause produces the Cartesian product of the tables involved in the join. The size of a Cartesian product result set is the number of rows in the first table multiplied by the number of rows in the second table. The common example is when company wants to combine each product with a pricing table to analyze each product at each price.
2. Inner Join A join that displays only the rows that have a match in both joined tables is known as inner Join. This is the default type of join in the Query and View Designer.
3. Outer Join A join that includes rows even if they do not have related rows in the joined table is an Outer Join. You can create three different outer join to specify the unmatched rows to be included:
1. Left Outer Join: In Left Outer Join all rows in the first-named table i.e. "left" table, which appears leftmost in the JOIN clause, are included. Unmatched rows in the right table do not appear.
2. Right Outer Join: In Right Outer Join all rows in the second-named table i.e. "right" table, which appears rightmost in the JOIN clause are included. Unmatched rows in the left table are not included.
3. Full Outer Join: In Full Outer Join all rows in all joined tables are included, whether they are matched or not.
4. Self Join This is a particular case when one table joins to itself, with one or two aliases to avoid confusion. A self join can be of any type, as long as the joined tables are the same. A self join is rather unique in that it involves a relationship with only one table. The common example is when company has a hierarchal reporting structure whereby one member of staff reports to another. Self Join can be Outer Join or Inner Join.

2.       What are primary keys and foreign keys?

·         Primary keys are the unique identifiers for each row.

·         They must contain unique values and cannot be null.

·         Due to their importance in relational databases, Primary keys are the most fundamental of all keys and constraints.

·         A table can have only one Primary key.

·         Foreign keys are both a method of ensuring data integrity and a manifestation of the relationship between tables.

3.       What is User Defined Functions? What kind of User-Defined Functions can be created?

·         User-Defined Functions allow defining its own T-SQL functions that can accept 0 or more parameters and return a single scalar data value or a table data type.

·         Different Kinds of User-Defined Functions created are:

1.       Scalar User-Defined Function A Scalar user-defined function returns one of the scalar data types. Text, ntext, image and timestamp data types are not supported. These are the type of user-defined functions that most developers are used to in other programming languages. You pass in 0 to many parameters and you get a return value.

2.       Inline Table-Value User-Defined Function An Inline Table-Value user-defined function returns a table data type and is an exceptional alternative to a view as the user-defined function can pass parameters into a T-SQL select command and in essence provide us with a parameterized, non-updateable view of the underlying tables.

3.       Multi-statement Table-Value User-Defined Function A Multi-Statement Table-Value user-defined function returns a table and is also an exceptional alternative to a view as the function can support multiple T-SQL statements to build the final result where the view is limited to a single SELECT statement. Also, the ability to pass parameters into a TSQL select command or a group of them gives us the capability to in essence create a parameterized, non-updateable view of the data in the underlying tables. Within the create function command you must define the table structure that is being returned. After creating this type of user-defined function, It can be used in the FROM clause of a T-SQL command unlike the behavior found when using a stored procedure which can also return record sets.

4.       What is Identity?

·         Identity (or AutoNumber) is a column that automatically generates numeric values.

·         A start and increment value can be set, but most DBA leave these at 1.

·         A GUID column also generates numbers; the value of this cannot be controlled.

·         Identity/GUID columns do not need to be indexed.

5.       What is Data Warehousing?

1. Subject-oriented, meaning that the data in the database is organized so that all the data elements relating to the same real-world event or object are linked together;
2. Time-variant, meaning that the changes to the data in the database are tracked and recorded so that reports can be produced showing changes over time;
3. Non-volatile, meaning that data in the database is never over-written or deleted, once committed, the data is static, read-only, but retained for future reporting.
4. Integrated, meaning that the database contains data from most or all of an organization's operational applications, and that this data is made consistent.