Technical Interview Questions and Answers :: Virtusa
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The UNIQUE KEY column restricts entry of duplicate values but entry of NULL value is allowed. In case of PRIMARY KEY columns entry of duplicate as well as
A View is a database object that is a logical representation of a table. It is derived from a table but has no storage space of its own and often may be used in the same manner as a table.
ROWID is the logical address of a row, and it is unique within the database.
INDEX is a general term for an SQL feature used primarily to speed up execution and impose UNIQUENESS upon data. You can use an index to gain fast access to specific information in a database table. An index is a structure that orders the values of one or more columns in a database table. The index provides pointers to the data values stored in specified columns of the table, and then orders those pointers according to the sort order you specify.
: An entity that maps over a result set and establishes a position on a single row within the result set. After the cursor is positioned on a row, operations can be performed on that row, or on a block of rows starting at that position. The most common operation is to fetch (retrieve) the current row or block of rows.
The try-catch block works the same way as Java. It is 3 sequence step Main, Try and Catch block. You execute a sequence of steps, if you faced unexpected exception/error you skip the processing and execute the catch block.
To define the Try-Catch block, follow the following steps:
- Create a new flow service using SoftwareAG designer.
- Create a new sequence and call it 'Main'.
- Create another two sequence under the 'main' sequence; call them, 'Try', and 'catch'.
Go to the properties of each sequence and configure the 'exit on' as follows:
* 'Success' for the 'Main' sequence.
*'Failure' for the 'try' sequence.
* 'Done' for the catch sequence.
The main sequence has the try, and Catch sequences. So by defining the 'exit on' parameter of for the main to 'Success', this means that if the first sequence (Try) finished successfully then exit the sequence 'Main' and the 'Catch' Block/sequence will not be executed.
The 'Try' sequence is configured to 'exit on' = 'failure', which means if one step failed, all the steps following the failed step in the 'Try' block will not be executed, and the code will jump to execute the 'Catch' block/sequence.
The 'Catch' block is configured to 'exit on' = 'done' which means that each step in the 'Catch' block must be executed regardless of the result of each step.
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i. These techniques can be used to invoke a function based on a string supplied by a user.
ii. To manipulate objects of unknown type through interfaces discovered through run-time type identification.
By definition, a node class is part of a class hierarchy. Not every class in a hierarchy needs to offer the same interface. In particular, a derived class can provide more member functions, and a sibling class can provide a completely different set of functions.
The simplest and most obvious way to specify an action in C++ is to write a function. If an action has to be delayed, it has to be transmitted elsewhere before being performed, it requires its own data that has to be combined with other actions etc.,
Then is often becomes attractive to provide the action in the form of a class that can execute the desired action and provide other services as well.