FileResult is used to Download physical File from Server to Client Machine
Refer below code having download functionality..
//post method
[Httppost]
public FileResult Download()
{
// logic
//return new FilePathResult(path of File, contentType);
return new FilePathResult(http://aabc.com/file/xyz.xlsx, “application/vnd.ms-excel”);
}
Temporary tables are useful when we want a manipulated data in tabular form at run time in query processing. A temporary table is visible to the session in which they were created and are automatically dropped when that session logs off.
Type of temp table
1) Local temp table: Syntax (create table #t).
If a temp table exist in a stored procedure it is automatically dropped when SP ends, i.e. temp table exist in current scope and current connection.
2) Global temp table: Syntax (create table ##t).
Global temp table can be accessed in any session in current connection and can be dropped in any session.
3) Temp variable: Syntax (create table @t)
A temp variable has all features of temp table but
It can’t be dropped manually,they are dropped automatically.
We can use a temp variable in user defined function but can’t do with temp table.
Suppose there is Datatable as below in C#.
Now I want to get all columns in form of array list.
To achieve this we will follow below approach
string[] columnNames = (from dc in dt.Columns.Cast()
select dc.ColumnName).ToArray();
Note : Here dt is Datatable.
ALTER TABLE TABLENAME
ADD ColumnName int NOT NULL DEFAULT(1)
GO
IEnumerable<T> Interface in C #
IEnumerable interface is a simple iteration over a collection of a specified type.It has Method GetEnumerator() that iterates through the collection.
Use: Mainly used to work with in memory data i.e List,Array
Example: IEnumerable<Product> products = db.employee.Take(3);
IQueryable Interface in C #
It is basically used to evaluate queries against a specific data source.
Use: Used to query database.e.g. iin LINQ
Example: IQueryable<Product> products = db.employee.Take(3);
Difference:
In IEnumerable All employees will be loaded After Loading all data program will filter
Query run on database- Select * from Employees
In IQueryable Data will be filterd on Database Program will get only top 3 recoreds
Query run on database- Select TOP 3 * from Employees
We have below List of string
List<string> lstString =new List<string>();
lstString.Add(“A”);
lstString.Add(“B”);
lstString.Add(“C”);
lstString.Add(“D”);
Problem : We have to find if string “A” exist in above List or not.
Solution : We will use below code to find a string
bool strExist = lstString.Any(x => x.Equals(A));
OUTPUT : true
Magic table hold the recently inserted values in the case of insert and to hold recently deleted values in the case of delete
Use: Often used in Trigger
e.
INSERT INTO emp
SELECT i.id, i.names
FROM INSERTED i // Magic Table
With help of extension method you can add a new method to an existing type without recompile and modifying existing type.
e.g.
string s = “hello”; string i = s.UpperCasefirstLater();
Result : Hello
Here UpperCasefirstLater is a extension method. see below code
public static class MyExtensions
{
public static string UpperCasefirstLater(this String str)
{
if (str.Length > 0)
{
char[] array = str.ToCharArray();
array[0] = char.ToUpper(array[0]);
return new string(array);
}
}
}
Case expression in SQL Server allows for values to be replaced in the result set based on comparison values.
e.g.
SELECT ID, Title= CASE Gender WHEN ‘M’ THEN ‘Mr’ WHEN ‘F’ THEN ‘Mrs’ END FROM EMPLOYEE.
COALESCE() function will return first non null value passed in it.
e.g.
Select COALESCE(NULL,NULL,’HERRY’,’THOMAS’)
OUTPUT : HERRY
Dot Net Tricks 