How to incement row id with identity to off - sql

Question

I am getting this error while i do select.
DECLARE #TopID INT
SELECT #TopID = MAX([QuestionId]) from [SurveyQuestions];
SELECT
#TopID = #TopID + 1
,[questiontext]
,[DeptID]
,[SurveyID]
FROM [SOSS].[dbo].[SurveyQuestions] where surveyid =80
A SELECT statement that assigns a value to a variable must not be
combined with data-retrieval operations.
I know there is a posibility to fix this error with identity set to ON.but i dont want that as my db is hosted in legecy application, changing this will make other things to break.

Answer 1

This has nothing to do with the identity. It has to do with the select. You have:
SELECT #TopID = #TopID + 1,
[questiontext], [DeptID], [SurveyID]
FROM [SOSS].[dbo].[SurveyQuestions]
WHERE surveyid = 80
This has an assignment and it returns values. I think you really want:
SELECT #TopId + (ROW_NUMBER() OVER (ORDER BY (SELECT NULL))) as rownum,
[questiontext], [DeptID], [SurveyID]
FROM [SOSS].[dbo].[SurveyQuestions]
WHERE surveyid = 80;
Note: If you actually want the results in a particular order, then add an ORDER BY both to the query and to the ROW_NUMBER().

Answer 2

It is the way you are selecting, you cant use operators in select with other columns being fetched. See this link for some explanation on what you are doing wrong.
I think what you really require is this :
DECLARE #TopID INT
SELECT #TopID = MAX([QuestionId]) from [SurveyQuestions];
SELECT
#TopID + 1
,[questiontext]
,[DeptID]
,[SurveyID]
FROM [SOSS].[dbo].[SurveyQuestions] where surveyid =80
EDIT :
Or a ROW_NUMBER based solution like :
DECLARE #TopID INT
SELECT #TopID = MAX([QuestionId]) from [SurveyQuestions];
SELECT
#TopID + ROW_NUMBER() OVER (ORDER BY (SELECT 1)) as TopID
,[questiontext]
,[DeptID]
,[SurveyID]
FROM [SOSS].[dbo].[SurveyQuestions] where surveyid =80
Improving a bit on the Previous Answer (combined into one query):
SELECT (
SELECT TOP 1 QuestionId
FROM SurveyQuestions
ORDER BY QuestionId DESC
)
+ ROW_NUMBER() OVER ( ORDER BY (SELECT 1)) AS TopID
, [questiontext], [DeptID], [SurveyID]
FROM [SOSS].[dbo].[SurveyQuestions]
WHERE surveyid = 80
SQL Fiddler
Another Alternative, combing your 2 queries :
SELECT
(SELECT MAX(ID) FROM ForgeRock) as MAx_Id
, ROW_NUMBER() OVER (ORDER BY (SELECT 1)) as Row_ID,
(SELECT TOP 1 ID FROM ForgeRock ORDER BY Id DESC) +
ROW_NUMBER() OVER (ORDER BY (SELECT 1)) as New_Id,
productName,
description
FROM
ForgeRock
SQL Fiddler