SQL游标进入无限循环

Posted 2021-05-03

此sql进入无限循环。

我找不到问题所在。我搜索了其他帖子，但是大多数帖子都错过了end标签之前的最后一个fetch语句。我敢肯定我看错了什么，但我不知道是什么。那我错过了什么吗？

下面是我的代码

    DECLARE 
    @counter INT = 1042,
    @overwrite_text NVARCHAR(250), 
    @sequence INT,
    @is_correct BIT,
    @score INT,
    --@form_question_id INT,
    @question_answer_id INT;

DECLARE cursor_form_answer CURSOR
FOR SELECT
      [overwrite_text]
      ,[sequence]
      ,[is_correct]
      ,[score]
      --,[form_question_id]
      ,[question_answer_id]
  FROM [form_question_answer];

OPEN cursor_form_answer;

FETCH NEXT FROM cursor_form_answer INTO 
    @overwrite_text, 
    @sequence,
    @is_correct,
    @score,
    --@form_question_id,
    @question_answer_id;

WHILE @@FETCH_STATUS = 0
    BEGIN

        INSERT INTO [form_question_answer] (overwrite_text, sequence, is_correct, score, form_question_id, question_answer_id)
        VALUES (@overwrite_text, @sequence, @is_correct, @score, @counter, @question_answer_id);

        SET @counter = @counter + 1;

        FETCH NEXT FROM cursor_form_answer INTO 
            @overwrite_text, 
            @sequence,
            @is_correct,
            @score,
            --@form_question_id,
            @question_answer_id;
    END;

CLOSE cursor_form_answer;

DEALLOCATE cursor_form_answer;

答案

这里完全不需要CURSOR。使用INSERT只需SELECT数据：

INSERT INTO [form_question_answer] (overwrite_text,
                                    [sequence],
                                    is_correct,
                                    score,
                                    form_question_id,
                                    question_answer_id)
SELECT [overwrite_text],
       [sequence],
       [is_correct],
       [score],
       --,[form_question_id]
       ROW_NUMBER() OVER (ORDER BY [form_question_id]),
       [question_answer_id]
FROM [form_question_answer];

但是我必须说，[[真的从表form_question_answer捕获数据，然后将其重新插入所述表中，这似乎很奇怪。