In SQL Server Query LEN() is used for to find out the length of character in String which is musty used in all the database. The LEN() function remove the code reusability in the query string. The LEN() functions return the length of char and calculates length using characters as defined by the input character set. LEN() uses bytes instead of characters and uses Unicode complete characters. The main purpose of the LEN() function to find out the size of any attribute of table. For Example we can Pass the table attributes as argument likes Select LEN (Employee_Name) from Employee. In this query LEN() function is find out the Employee_Name String length.