If you have a situation where you want to add a column into a table in SQL Server, it would be a good idea to perform a check first if a column has already existed in a table. Otherwise, if you try to add a duplicate column, you may get an error message when you try to add a column via SQL query.
Do you want to know if a function has already exists in sql server? This quick check if condition may come handy especially if you want to run a batch sql query.
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[my_function]') AND type IN ( N'FN', N'IF', N'TF', N'FS', N'FT' )) DROP FUNCTION [dbo].[my_function] GO