Microsoft SQL IDENTITY

When you want to get auto-generated ID value from table which you make inserting data at the same time, you can make two ways. One of the ways to meet this requirement is using Sql Identity and @@Identity keyword. Second ways is using NEWID() keyword.

Firstly you need to create table like that ...

CREATE TABLE Customer
(
CustomerID INT IDENTITY(1, 1) NOT NULL,
CustomerName VARCHAR(25) NULL,
PhoneNo VARCHAR(20) NULL
)

Then, you need to make storeprocedure ....

CREATE PROCEDURE getCustomerIDAfterInsertCustomer
@CustomerID INT = NULL OUTPUT,
@CustomerName VARCHAR(25),
@PhoneNo VARCHAR(20)
AS
BEGIN
INSERT INTO Customer (CustomerName, PhoneNo) VALUES (@CustomerName, @PhoneNo)
SET @CustomerID = @@IDENTITY
SELECT @CustomerID AS CustomerID
END

Then, execute procedure like that ...

DECLARE @CustomerID AS INT
EXEC getCustomerIDAfterInsertCustomer @CustomerID OUTPUT, 'Customer 1', '654-9956213'

If you make delete this table, you will also need to make reindex, so you should do like that ....

DELETE FROM Customer
DBCC CHECKIDENT(Customer, RESEED, 0)

Way to use c# datetime.

When you want to get number of days according to given date,
you can use this function in c# .net

public int getNumberOfDayByGivenDate(DateTime dtGivenDate)
{
DateTime dtMyDate = DateTime.Parse("16/10/2009");
TimeSpan tsGetNumber = dtGivenDate.Subtract(dtMyDate);
return tsGetNumber.Days;
}

When you want to get date format data according to given integer number,
you can use below function in c# .net

public DateTime getDateByGivenNumber(int GivenNumber)
{
DateTime dtMyDate = DateTime.Parse("16/10/2009");
TimeSpan tsByGivenNumber = new TimeSpan(GivenNumber, 0, 0, 0);
return dtMyDate.Add(tsByGivenNumber);
}