How to add space between two string of two text-boxes ?

Don't.
If you get information in separated fields, store them in separated fields.
Otherwise, you are throwing information away, and making assumptions about the information!

Store them in separate fields, and you can retrieve the "first name" for friendly greetings:

string greet = "Hi " + firstName;

Or add an honorific:

string greet = "Dear Mr " + lastName;

You can retrieve the "full name" from the DB at any time:

SELECT FirstName + ' ' + LastName AS [Full Name] FROM MyTable

use like below

string Name = txtFirstName.Text.Trim() + " " + txtLastName.Text.Trim();

you just use variable Name and pass it into database.


Thanks,
-RG

During insert

insert into TableName (FullName) values (@firstName+' '+@LastName)

pass textbox values to @firstName and @LastName

During Select

select FirstName+' 'LastName as FullName from TableName

string fullName = txtFirstName.Text + " " + txtLastName.Text;

But how do you get the First Name and Last Name back as separate fields to be displayed back? Store them as separate columns in the database.