不断出现“光标是只读的”

Question

我的代码看起来很先进。

我想使用唯一的计数器（不等于 {1,2,3,...}）更新特定字段。

我不断收到错误“光标为只读”。

另外：有没有更简单的方法？

declare @MaxVal int = NULL
declare @fetchVal int = NULL
select @MaxVal = MAX(tp_Id)+1 from [<tableContainingInitialMaxval>] 
/** some default **/

DECLARE curs01 CURSOR 
for select @maxVal + row_number() OVER (order by [<someUniqueField>]) from [<table2update>];
(used FOR UPDATE OF [<field2update>] but that made no difference)

open curs01
FETCH NEXT FROM curs01 INTO @fetchVal;
WHILE @@FETCH_STATUS = 0
    begin
        update [<table2update>] set [<field2update>] =  @fetchVal 
        WHERE CURRENT OF curs01;
        FETCH NEXT FROM curs01 INTO @fetchVal;
    end;
CLOSE curs01;
DEALLOCATE curs01;
GO 

Answer 1

为此，您不需要光标。

DECLARE @MaxVal INT = NULL

SELECT @MaxVal = MAX(tp_Id) + 1
FROM   tableContainingInitialMaxval;

WITH CTE
     AS (SELECT *,
                @maxVal + row_number() OVER (ORDER BY someUniqueField) AS rn
         FROM   table2update)
UPDATE CTE
SET    field2update = rn