Aggregate Functions in SQL Server

T-SQL

Let’s create a SampleDB database fist with SQL Management Studio. Now create a table in SampleDB.

Insert Sample Data:

Aggregate Functions in SQL Server

COUNT (Transact-SQL)

Returns the number of items in a group. COUNT always returns an int data type value. Continue reading “Aggregate Functions in SQL Server”

IEnumerable Vs IQueryable

C# Basic, MVC

Differences between them based on their properties :

IEnumerable

  1. NamespaceSystem.Collections Namespace
  2. Derives from: No base interface
  3. Deferred Execution : Supported
  4. Lazy Loading : Not Supported
  5. How does it work : While querying data from database, IEnumerable execute select query on server side, load data in-memory on client side and then filter data. Hence does more work and becomes slow.
  6. Suitable for : LINQ to Object and LINQ to XML queries.
  7. Custom Query : Doesn’t supports.
  8. Extension method parameter : Extension methods supported in IEnumerable takes functional objects.
  9. When to use : When querying data from in-memory collections like List, Array etc.
  10. Best Uses : In-memory traversal

Continue reading “IEnumerable Vs IQueryable”

List few advantages of Stored Procedure.

QA-SQL Server
  • Stored procedure can reduced network traffic and latency, boosting application performance.
  • Stored procedure execution plans can be reused, staying cached in SQL Server’s memory, reducing server overhead.
  • Stored procedures help promote code reuse.
  • Stored procedures can encapsulate logic. You can change stored procedure code without affecting clients.
  • Stored procedures provide better security to your data.

What is Cross Join?

QA-SQL Server

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.

What is Self Join?

QA-SQL Server

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 have a hierarchal reporting structure whereby one member of staff reports to another.