SQL Server 2005：插入查询返回操作数类型冲突：ntext与smallint不兼容

Question

I have what I hope is a quick question. Haven't found working code for this, and I'm at a little bit of a loss.

I'm working with an old database on SQL Server 2005. It has a dynamic questionnaire (or a thousand, actually... long story), and each question can have the answer stored as either a smallint or as ntext.

The current "answers" table is as follows:

AnswerID (PK, int, not null)
EvalID (int, null)
QuestionID (int, null)
NumericAnswer (smallint, null)
TextAnswer (ntext, null)

(Yes, I know ntext is deprecated. It's an old table.)

This table now has over 300,000 records in it, and is getting really large. So I'm looking for more efficient ways to store the data, and decided to do a little experiment with moving everything to a single sql_variant field (currently, each row can have data in just one of the two answer columns, not both).

So I made another table, called AnswersTest :

AnswerID (PK, int, not null)
EvalID (int, null)
QuestionID (int, null)
AnswerGiven (sql_variant, null)

... and I'm now trying to get all of the existing data from Answers to AnswersTest , preferably in their original order... so I'm running an insert query, and it's not working. I've tried both the following:

INSERT INTO AnswersTest (EvalID, QuestionID, AnswerGiven)
SELECT EvalID, QuestionID, ISNULL(NumericAnswer,TextAnswer) AS AnswerGiven FROM Answers ORDER BY AnswerID

...and

INSERT INTO AnswersTest (EvalID, QuestionID, AnswerGiven)
SELECT EvalID, QuestionID, CONVERT(ntext,CASE WHEN NumericAnswer IS NULL THEN TextAnswer ELSE NumericAnswer END) AS AnswerGiven FROM Answers ORDER BY AnswerID

In both cases, I get the following: Operand type clash: ntext is incompatible with smallint

I know there must be a simple answer to this... I'm just drawing a blank (it's been a couple of months since I've had to do anything much with TSQL), and I can't find a working answer through searching. Please help. :)

EDIT: Found an answer through trial and error...

The answer may not have been the best one (and it may jump through some unnecessary hoops), but it's a one-time query and it works. :)

INSERT INTO AnswersTest (EvalID, QuestionID, AnswerGiven)
SELECT EvalID, QuestionID, CASE WHEN CONVERT(sql_variant,NumericAnswer) IS NULL THEN CONVERT(sql_variant,CONVERT(varchar(8000),TextAnswer)) ELSE CONVERT(sql_variant,NumericAnswer) END AS AnswerGiven FROM Answers ORDER BY AnswerID

(Note: I tried varchar(max) , but that wasn't allowed. The answers weren't all that long, though... nobody writes essays in these surveys... so I just changed it to varchar(8000) , and that worked).

Thanks for reading, and sorry to take up your time! :)

Answer 1

Faced Similar Error when I accidentally gave string values to column defined as int. Please rearrange the values and Table fields in the insert statement For ex

Insert into Table (int,string) values (string,int)

will not work and generate the error as stated above. So re arrange it in respective manner.

 Insert into Table (int,string) values (int,string)

Answer 2

This link describes the difference between ntext and nvarchar(max). Is does mention that the ntext is being deprecated. It also talk about the nvarchar(max) being stored within your table making the queries faster. You might want to try using the variation of separate fields of numericanswer and textanswer and see where it gets you from a performance perspective.