Need Help With Stored Proc. Pretty Simple For An Experienced Person

Can someone help me rewrite this query? Basically I need to check if the name stored in "CustomerName" already exist in the table "Renter". If it does not then I ncan insert the new customer name

into the data table "Renter". If the value in "CustomerName" already exists in the database, then I need to bypass the "INSERT" and somehow return a value indicating that the insert was not performed. How can I do this. Here is the

query I currently have for performing the insert.

CREATE PROCEDURE [dbo].[VacancyGet]

(

@CustomerName nvarchar(100),

@ClientCode nvarchar(10)

)

AS

INSERT INTO Renter

(

CustomerName,

ClientCode,

)

VALUES

(

@CustomerName,

@ClientCode,

)