Question

I have a legacy code which used a Table called MyTable which **has only 6 records**.

Here is SQl code:

USe MyDatabase
GO

DECLARE @ANubmer as  Varchar(100)
DECLARE @BNumber as Varchar(100)


DECLARE MyCursor  CURSOR FOR
SELECT Anumber,BNumber
 FROM MyTable
 ORDER BY 
 s.ANumber,date1

OPEN SurveyCursor
FETCH NEXT FROM MyCursor INTO @ANubmer, @BNumber

 select 'CID='+@ANumber+' Avatar='+ @BNubmer


WHILE @@FETCH_STATUS = 0
BEGIN

 FETCH NEXT FROM MyCursor INTO @ANubmer, @BNumber                   

 select 'CID='+@ANumber+' Avatar='+ @BNubmer
END

问题在于代码返回7行。

Answer 1

把第二个＆＃39; FETCH＆＃39;在＆＃39;下方选择＆＃39;循环中的语句。从本质上讲，它应该是＆＃39;中的最后一句话。循环。

同样......抛弃第一个选择语句。你应该把所有东西放在一个循环中。

抓取 - ＆gt;而 - ＆gt;选择 - ＆gt;取

  WHILE @@FETCH_STATUS = 0
    BEGIN



     select 'CID='+@ANumber+' Avatar='+ @BNubmer

     FETCH NEXT FROM MyCursor INTO @ANubmer, @BNumber
    END

更正完整脚本

USe MyDatabase
GO

DECLARE @ANubmer as  Varchar(100)
DECLARE @BNumber as Varchar(100)


DECLARE MyCursor  CURSOR FOR
SELECT Anumber,BNumber
 FROM MyTable
 ORDER BY 
 s.ANumber,date1

OPEN SurveyCursor
FETCH NEXT FROM MyCursor INTO @ANubmer, @BNumber


WHILE @@FETCH_STATUS = 0
BEGIN


 select 'CID='+@ANumber+' Avatar='+ @BNubmer


 FETCH NEXT FROM MyCursor INTO @ANubmer, @BNumber 
END

建议的优化

使用GOTO的一个提取语句

关闭/取消分配

USe MyDatabase
GO

DECLARE @ANubmer as  Varchar(100)
DECLARE @BNumber as Varchar(100)


DECLARE MyCursor  CURSOR FOR
SELECT Anumber,BNumber
 FROM MyTable
 ORDER BY 
 s.ANumber,date1

OPEN SurveyCursor

GOTO FetchNext;


WHILE @@FETCH_STATUS = 0
BEGIN


 select 'CID='+@ANumber+' Avatar='+ @BNubmer

FetchNext:
 FETCH NEXT FROM MyCursor INTO @ANubmer, @BNumber 
END

CLOSE MyCursor
DEALLOCATE MyCursor

Answer 2

为什么不简单地执行Select，它将返回游标返回的确切内容，但速度会快得多。

一个简单的选择看起来像......

select 'CID='+ CAST(Anumber AS VARCHAR(100)) + ' Avatar='+ CAST(BNumber  AS VARCHAR(100)) 
FROM MyTable
ORDER BY ANumber , date1

为了处理空值，我会做类似的事情......

select 'CID='   + CAST(ISNULL(Anumber,'No value') AS VARCHAR(100)) 
    + ' Avatar='+ CAST(ISNULL(BNumber,'No value') AS VARCHAR(100)) 
FROM MyTable
ORDER BY ANumber , date1

游标返回1个额外记录

2 个答案: