I don't seem to make it work. See below. What is the purpose of the output param being listed twice?

Thanks

declare @id nvarchar(50), @sql nvarchar(500), @table varchar (50)
set @table = 'intake'
set @sql = N'select in_lname from ' + @table + ' where in_id = 7'

exec sp_executesql @sql, N'@id nvarchar(50) output', @id output

if @id is null
  print 'null'
else
  print @id

Prints null every time.

>See How to return a value from dynamicaly executed T-SQL code FAQ #8130
>
>>I have a stored proc that uses the following code:
>>

>>set @var = (select col from table where pk = @param)
>>

>>
>>What I would like to do is make 'table' a variable to make the sp more generic. Something like this would be nice (but this won't work).
>>

>>set @sql = 'select col from ' + @table + ' where pk = ' + @param
>>set @var = (exec sp_executesql @sql)
>>

>>
>>Any ideas how to set a variable to the result of a dynamically constructed sql statement?
>>
>>TIA
>>
>>John