问题
This code works fine and does exactly what I want, which is to sum the Qty * Price for each instance of the dynamic query.
But when I add an IIF statement it breaks. What I am trying to do is the same thing as above but when the transaction type is 'CO' set the sum to a negative amount.
回答1:
The problem turned out to be the NVARCHAR(4000) type of @sql, limiting its length to 4000 characters: the query got truncated at some random place after adding another long chunk to it.
DECLARE @sql NVARCHAR(MAX) solves the problem, allowing a dynamic query of any size below 2GB.
来源：https://stackoverflow.com/questions/14862086/trouble-with-dynamic-t-sql-iif-statement