I need to update only the new records and the rest are unchanged

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SQL

Good afternoon
I have a stroreprocedure that updates a column in a table when another table is changed, but when that happens it changes the volumes all referring to the table id and I didn't want that to happen, I just wanted the new records to be changed
Thank you in advance for any help you can give me

What I have tried:

<pre>USE [MiniPayroll]
GO
/****** Object:  StoredProcedure [dbo].[sp_SubMensal_update]    Script Date: 09-04-2021 15:47:30 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:		<Author,,Name>
-- Create date: <Create Date,,>
-- Description:	<Description,,>
-- =============================================
ALTER PROCEDURE [dbo].[sp_SubMensal_update]


	
AS
BEGIN
	UPDATE      EmpAttendance
SET   SubDiario = 

(
SELECT SubDiario
FROM EmpSalary
where EmpAttendance.EmpId = EmpSalary.EmpId) 

END