Posts

Showing posts from April, 2015

Difference between array, arraylist, List, Hashtable, Dictionary and SortedList in c#

-
Basic difference is that arrays are of fixed size. Whereas an ArrayList implements the list data structure and can dynamically grow. While arrays would be more performance that a list, a list would be far more flexible since you don't need to know the required size initially. Array - represents an old-school memory array - kind of like a alias for a normal type[] array. Can enumerate. Can't grow automatically. I would assume very fast insertion, retrieve and speed. ArrayList - automatically growing array. Adds more overhead. Can enum., probably slower than a normal array but still pretty fast. These are used a lot in .NET List - one of my favorites - can be used with generics, so you can have a strongly typed array, e.g. List . Other than that, acts very much like ArrayList. Hashtable - plain old hashtable. O(1) to O(n) worst case. Can enumerate the value and keys properties, and do key/val pairs. Dictionary - same as above only strongly typed via generics, such a...
Post a Comment
Read more

What are Session state modes in ASP.NET?

-
ASP.NET supports different session state storage options: In-Process is the default approach. It stores session state locally on same web server memory where the application is running.  State-server mode stores session state in a process other than the one where application is running. Naturally, it has added advantages that session state is accessible from multiple web servers in a Web Farm and also session state will remain preserved even web application is restarted.  SQLServer mode stores session state in SQL Server database. It has the same advantages as that of State-server. Custom modes allows to define our custom storage provider. Off mode disables session storage.
Post a Comment
Read more

What is the difference between custom controls and user controls?

-
Following is the difference between custom controls and user controls Custom controls are basically compiled code i.e. DLLs. These can be easily added to toolbox, so it can be easily used across multiple projects using drag and drop approach. These controls are comparatively hard to create. But User Controls (.ascx) are just like pages (.aspx). These are comparatively easy to create but tightly couple with respect to User Interface and code. In order to use across multiple projects, we need to copy and paste to the other project as well.
Post a Comment
Read more

What is the concept of Postback in ASP.NET?

-
A postback is a request sent from a client to server from the same page user is already working with. ASP.NET was introduced with a mechanism to post an HTTP POST request back to the same page. It's basically posting a complete page back to server (i.e. sending all of its data) on same page. So, the whole page is refreshed. Another concept related to this approach is "Callback" that is also asked sometimes during a technical interview question.
Post a Comment
Read more

What is difference between DELETE and TRUNCATE commands?

-
Delete command removes the rows from a table based on the condition that we provide with a WHERE clause. Truncate will actually remove all the rows from a table and there will be no data in the table after we run the truncate command.   1. TRUNCATE: TRUNCATE is faster and uses fewer system and transaction log resources than DELETE. TRUNCATE removes the data by deallocating the data pages used to store the table's data, and only the page deallocations are recorded in the transaction log. TRUNCATE removes all rows from a table, but the table structure, its columns, constraints, indexes and so on, remains. The counter used by an identity for new rows is reset to the seed for the column. You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint. Because TRUNCATE TABLE is not logged, it cannot activate a trigger.  TRUNCATE cannot be rolled back.  TRUNCATE is DDL Command. TRUNCATE Resets identity of the table   2. DELETE:  DELETE removes row...
Post a Comment
Read more

What is SQL Server Agent in sql?

-
SQL Server agent plays an important role in the day- to-day tasks of a database administrator (DBA).  It is often overlooked as one of the main tools for SQL Server management.  Its purpose is to ease the implementation of tasks for the DBA, with its full- function scheduling engine, which allows you to schedule your own jobs and scripts.
Post a Comment
Read more

How to implement one-to-one, one-to-many and many-to-many relationships while designing tables?

-
One-to-One relationship can be implemented as a single table and rarely as two tables with primary and foreign key relationships. One-to-Many relationships are implemented by splitting the data into two tables with primary key and foreign key relationships.  Many- to-Many relationships are implemented using a junction table with the keys from both the tables forming the composite primary key of the junction table
Post a Comment
Read more

What is NOT NULL Constraint in sql?

-
A NOT NULL constraint enforces that the column will not accept null values. The NOT NULL constraints are used to enforce domain integrity, as the check constraints.
Post a Comment
Read more

Advantages of using Stored Procedures?

-
1. Stored procedure can reduced network traffic and latency, boosting application performance. 2. Stored procedure execution plans can be reused, staying cached in SQL Server's memory, reducing server overhead. 3. Stored procedures help promote code reuse. 4. Stored procedures can encapsulate logic. You can change stored procedure code without affecting clients. 5. Stored procedures provide better security to your data.
Post a Comment
Read more

What is PRIMARY KEY in sql?

-
A PRIMARY KEY constraint is a unique identifier for a row within a database table.  Every table should have a primary key constraint to uniquely identify each row and only one primary key constraint can be created for each table.  The primary key constraints are used to enforce entity integrity.
Post a Comment
Read more

What is Log Shipping in sql?

-
Log shipping is the process of automating the backup of database and transaction log files on a production SQL server, and then restoring them onto a standby server. Enterprise Editions only supports log shipping. In log shipping the transactional log file from one server is automatically updated into the backup database on the other server. If one server fails, the other server will have the same db and can be used this as the Disaster Recovery plan. The key feature of log shipping is that it will automatically backup transaction logs throughout the day and automatically restore them on the standby server at defined interval.  
Post a Comment
Read more