Check out example codes for "sql server 2012 create or alter procedure". It will help you in understanding the concepts better.

Code Example 1

IF OBJECT_ID('spCallSomething') IS NULL
    EXEC('CREATE PROCEDURE spCallSomething AS SET NOCOUNT ON;')
GO

ALTER PROCEDURE spCallSomething ... 
--instead of DROP/CREATE

Learn ReactJs, React Native from akashmittal.com