How SQL Server handles when a SELECT statement returns multiple records to assign a value to a variable

select|server| variable | statement declare @user nvarchar (20)
Select @user = ' User1 '
Use CountMe
/* To determine whether the user exists * *
DECLARE @userweek int
Select @userweek =[week] from base where userid= @user
SELECT @ @rowcount
If @ @rowcount =0
Return
Select @userweek

The result of the final @userweek print is to record the value of the week field with the user name User1.

And when we select all the records with the following statement (no where limit)
declare @user nvarchar (20)
Select @user = ' User1 '
Use CountMe
/* To determine whether the user exists * *
DECLARE @userweek int
Select @userweek =[week] from base
SELECT @ @rowcount
If @ @rowcount =0
Return
Select @userweek

The last @userweek print value is the week field value of the last record in all returned records