sql - The data types varchar and int are incompatible in the concat operator -

i've been stuck past 2 days execute give error:

the data types varchar , int incompatible in concat operator

here table:

create table salestable (      id int identity(1,1) not null primary key,       empid char(5),       datesold date,       monthonly varchar(50),       amount money ) 

this code inserts dummy record dbo.salestable working in salestable, debug , step code give debug , understanding code

declare @outercounter int = 1 declare @innercounter int = 1  while @outercounter <= (select count(name) namestable) begin      while @innercounter <= datediff(day, getdate() -datepart(day, getdate()), {fn concat('12/31/',datepart(year,getdate()))})     begin          insert salestable (empid, datesold, monthonly, amount)          values (@outercounter,                  getdate() - datepart(day, getdate()) + @innercounter,                 datename(month, getdate() - datepart(day, getdate()) + @innercounter),                 rand() * 10000)         set @innercounter =  @innercounter +1                end      set @outercounter = @outercounter + 1     set @innercounter = 1 end  select * dbo.salestable 

fn concat('12/31/',cast(datepart(year,getdate()) varchar(10))) 

try this