ADO.NET ExecuteScalar in SqlCommand Object
ExecuteScalar() in SqlCommand Object is used for get a single value from Database after its execution. It executes SQL statements or Stored Procedure and returned a scalar value on first column of first row in the Result Set. If the Result Set contains more than one columns or rows , it takes only the first column of first row, all other values will ignore. If the Result Set is empty it will return a Null reference.
It is very useful to use with aggregate functions like Count(*) or Sum() etc. When compare to ExecuteReader() , ExecuteScalar() uses fewer System resources.
connetionString = "Data Source = ServerName; Initial Catalog = DatabaseName; User ID = UserName; Password = Password"
sql = "Your SQL Statement Here like Select Count(*) from product"
You have to replace the string with your realtime variables.