Error: An expression of non-boolean type specified in a context where a condition is expected, near ')' SQL Server

Question

Question built from this question (Still return records if unsatisfied cross join condition). The database for this question is extended and provided below.

My desired output is to show the first four things bought in a month, and if bought on the same day, output the one with a larger amount.

I have added d_thing_id to see which thing, bought on the same day, has a larger amount.

However, I keep getting an error

An expression of non-boolean type specified in a context where a condition is expected, near ')'

Data:

create table Sales
(
    Date datetime, 
    C_Name char(1), 
    Thing varchar(100), 
    Amount int
)

insert into Sales (Date, C_Name, Thing, Amount) 
values   ('2021-02-21','A','Fruit', 20)
        ,('2021-02-22','A','Bottle', 15)
        ,('2021-02-22','A','Straw', 7)
        ,('2021-02-26','A','Doll' , 31)
        ,('2021-02-27','A','Drink', 29)
        ,('2021-02-27','A','Bread', 30)
        ,('2021-02-28','B','Book' , 67)
        ,('2021-06-03','B','Fruit' , 100)
        ,('2021-06-13','B','Shoes' , 10)
        ,('2021-06-10','C','Shoes', 90)
        ,('2021-07-07','A','Tablet', 4)
        ,('2021-07-11','A','Chair' , 77)
        ,('2021-07-11','A','Cushion', 43)
        ,('2021-07-20','A','Sofa' , 37)
        ,('2021-07-21','A','Coat' , 66)

Code

with d1(Date, C_Name, Thing, Amount, Month) as
(
    select *, month(Date) as Month
    from Sales
),
d2 (thing_id, Month, C_Name, Thing) as
(
    select 
        'Thing' + cast(row_number() over (partition by C_Name, Month
                                          order by Date) as varchar(10)) as thing_id
           ,Month
           ,C_Name
           ,Thing
    from d1
    where 
        (select row_number() over (partition by C_Name, Month, Date
                                   order by Date, Amount desc) as d_thing_id
         from d1
         where d_thing_id = 1)
)
select *
from d2 
pivot 
    (min(Thing) 
         for thing_id in ([Thing1], [Thing2], [Thing3])
    ) as p;

EDIT

My expected output

month C_Name Thing1 Thing2 Thing3 Thing4
2       A    Fruit  Bottle  Doll  Bread
2       B    Fruit
6       B    Fruit  Shoes
6       C    Shoes
7       A    Tablet Chair  Sofa  Coat

Answer 1

this where clause has no operator

  where   (select row_number() over 
                  (
                      partition by C_Name, Month, Date
                      order by Date, Amount DESC
                  ) as d_thing_id
             from d1
             where d_thing_id = 1
            )

It should be more like this for example

  where   (select row_number() over 
                  (
                      partition by C_Name, Month, Date
                      order by Date, Amount DESC
                  ) as d_thing_id
             from d1
             where d_thing_id = 1
            ) = something