下面是我的解决方案，它使用了一个无限循环、BREAK语句和@@ROWCOUNT函数。没有游标或临时表是必要的，我只需要写一个查询，以获得下一行在@databases表:

declare @databases table
(
    DatabaseID    int,
    [Name]        varchar(15),   
    [Server]      varchar(15)
);


-- Populate the [@databases] table with test data.
insert into @databases (DatabaseID, [Name], [Server])
select X.DatabaseID, X.[Name], X.[Server]
from (values 
    (1, 'Roger', 'ServerA'),
    (5, 'Suzy', 'ServerB'),
    (8675309, 'Jenny', 'TommyTutone')
) X (DatabaseID, [Name], [Server])


-- Create an infinite loop & ensure that a break condition is reached in the loop code.
declare @databaseId int;

while (1=1)
begin
    -- Get the next database ID.
    select top(1) @databaseId = DatabaseId 
    from @databases 
    where DatabaseId > isnull(@databaseId, 0);

    -- If no rows were found by the preceding SQL query, you're done; exit the WHILE loop.
    if (@@ROWCOUNT = 0) break;

    -- Otherwise, do whatever you need to do with the current [@databases] table row here.
    print 'Processing @databaseId #' + cast(@databaseId as varchar(50));
end

-- [PO_RollBackOnReject]  'FININV10532'
alter procedure PO_RollBackOnReject
@CaseID nvarchar(100)

AS
Begin
SELECT  *
INTO    #tmpTable
FROM   PO_InvoiceItems where CaseID = @CaseID

Declare @Id int
Declare @PO_No int
Declare @Current_Balance Money


While (Select ROW_NUMBER() OVER(ORDER BY PO_LineNo DESC) From #tmpTable) > 0
Begin
        Select Top 1 @Id = PO_LineNo, @Current_Balance = Current_Balance,
        @PO_No = PO_No
        From #Temp
        update PO_Details
        Set  Current_Balance = Current_Balance + @Current_Balance,
            Previous_App_Amount= Previous_App_Amount + @Current_Balance,
            Is_Processed = 0
        Where PO_LineNumber = @Id
        AND PO_No = @PO_No
        update PO_InvoiceItems
        Set IsVisible = 0,
        Is_Processed= 0
        ,Is_InProgress = 0 , 
        Is_Active = 0
        Where PO_LineNo = @Id
        AND PO_No = @PO_No
End
End

首先，你应该绝对确定你需要遍历每一行——基于行集的操作在我能想到的任何情况下都会执行得更快，通常会使用更简单的代码。

根据您的数据，可能只使用SELECT语句循环，如下所示:

Declare @Id int

While (Select Count(*) From ATable Where Processed = 0) > 0
Begin
    Select Top 1 @Id = Id From ATable Where Processed = 0

    --Do some processing here

    Update ATable Set Processed = 1 Where Id = @Id 

End

另一种方法是使用临时表:

Select *
Into   #Temp
From   ATable

Declare @Id int

While (Select Count(*) From #Temp) > 0
Begin

    Select Top 1 @Id = Id From #Temp

    --Do some processing here

    Delete #Temp Where Id = @Id

End

您应该选择的选项实际上取决于数据的结构和容量。

注意:如果您正在使用SQL Server，您将更好地使用:

WHILE EXISTS(SELECT * FROM #Temp)

使用COUNT将不得不触及表中的每一行，EXISTS只需要触及第一行(参见Josef的回答)。

我真的不明白为什么你需要使用可怕的光标。 但是如果你使用的是2005/2008版本的SQL Server，还有另一种选择 使用递归

declare @databases table
(
    DatabaseID    int,
    Name        varchar(15),   
    Server      varchar(15)
)

--; Insert records into @databases...

--; Recurse through @databases
;with DBs as (
    select * from @databases where DatabaseID = 1
    union all
    select A.* from @databases A 
        inner join DBs B on A.DatabaseID = B.DatabaseID + 1
)
select * from DBs

你可以使用while循环:

While (Select Count(*) From #TempTable) > 0
Begin
    Insert Into @Databases...

    Delete From #TempTable Where x = x
End

以下是我的做法:

Select Identity(int, 1,1) AS PK, DatabaseID
Into   #T
From   @databases

Declare @maxPK int;Select @maxPK = MAX(PK) From #T
Declare @pk int;Set @pk = 1

While @pk <= @maxPK
Begin

    -- Get one record
    Select DatabaseID, Name, Server
    From @databases
    Where DatabaseID = (Select DatabaseID From #T Where PK = @pk)

    --Do some processing here
    -- 

    Select @pk = @pk + 1
End

[编辑]因为我可能在第一次读这个问题时跳过了“变量”这个词，这里是一个更新的回答…

declare @databases table
(
    PK            int IDENTITY(1,1), 
    DatabaseID    int,
    Name        varchar(15),   
    Server      varchar(15)
)
-- insert a bunch rows into @databases
--/*
INSERT INTO @databases (DatabaseID, Name, Server) SELECT 1,'MainDB', 'MyServer'
INSERT INTO @databases (DatabaseID, Name, Server) SELECT 1,'MyDB',   'MyServer2'
--*/

Declare @maxPK int;Select @maxPK = MAX(PK) From @databases
Declare @pk int;Set @pk = 1

While @pk <= @maxPK
Begin

    /* Get one record (you can read the values into some variables) */
    Select DatabaseID, Name, Server
    From @databases
    Where PK = @pk

    /* Do some processing here */
    /* ... */ 

    Select @pk = @pk + 1
End