If you are using SQL Server, Use the LEN (Length) function:
SELECT EmployeeName FROM EmployeeTable WHERE LEN(EmployeeName) > 4
MSDN for it states:
Returns the number of characters of the specified string expression,
excluding trailing blanks.
Here’s the link to the MSDN
For oracle/plsql you can use Length(), mysql also uses Length.
Here is the Oracle documentation:
http://www.techonthenet.com/oracle/functions/length.php
And here is the mySQL Documentation of Length(string):
http://dev.mysql.com/doc/refman/5.1/en/string-functions.html#function_length
For PostgreSQL, you can use length(string) or char_length(string). Here is the PostgreSQL documentation:
http://www.postgresql.org/docs/current/static/functions-string.html#FUNCTIONS-STRING-SQL