一个人如何能为一个表中的每一行调用一个存储过程,其中一行的列是sp的输入参数,而无需使用游标?
一个人如何能为一个表中的每一行调用一个存储过程,其中一行的列是sp的输入参数,而无需使用游标?
Answers:
一般来说,我总是在寻找一种基于集合的方法(有时以更改模式为代价)。
但是,此片段确实有它的位置。
-- Declare & init (2008 syntax)
DECLARE @CustomerID INT = 0
-- Iterate over all customers
WHILE (1 = 1)
BEGIN
-- Get next customerId
SELECT TOP 1 @CustomerID = CustomerID
FROM Sales.Customer
WHERE CustomerID > @CustomerId
ORDER BY CustomerID
-- Exit loop if no more customers
IF @@ROWCOUNT = 0 BREAK;
-- call your sproc
EXEC dbo.YOURSPROC @CustomerId
END
您可以执行以下操作:通过例如CustomerID(使用AdventureWorks Sales.Customer
示例表)订购表,并使用WHILE循环遍历那些客户:
-- define the last customer ID handled
DECLARE @LastCustomerID INT
SET @LastCustomerID = 0
-- define the customer ID to be handled now
DECLARE @CustomerIDToHandle INT
-- select the next customer to handle
SELECT TOP 1 @CustomerIDToHandle = CustomerID
FROM Sales.Customer
WHERE CustomerID > @LastCustomerID
ORDER BY CustomerID
-- as long as we have customers......
WHILE @CustomerIDToHandle IS NOT NULL
BEGIN
-- call your sproc
-- set the last customer handled to the one we just handled
SET @LastCustomerID = @CustomerIDToHandle
SET @CustomerIDToHandle = NULL
-- select the next customer to handle
SELECT TOP 1 @CustomerIDToHandle = CustomerID
FROM Sales.Customer
WHERE CustomerID > @LastCustomerID
ORDER BY CustomerID
END
只要您可以ORDER BY
在某列上定义某种形式的表,那它就可以与任何表一起使用。
DECLARE @SQL varchar(max)=''
-- MyTable has fields fld1 & fld2
Select @SQL = @SQL + 'exec myproc ' + convert(varchar(10),fld1) + ','
+ convert(varchar(10),fld2) + ';'
From MyTable
EXEC (@SQL)
好的,所以我永远不会将这样的代码投入生产,但是它确实满足您的要求。
Marc的回答很好(如果可以解决的话,我会对此发表评论!)
只是以为我要指出的是,更改循环可能会更好,因此SELECT
仅存在一次(在实际情况下,我需要这样做SELECT
非常复杂,将其写入两次是有风险的维护问题)。
-- define the last customer ID handled
DECLARE @LastCustomerID INT
SET @LastCustomerID = 0
-- define the customer ID to be handled now
DECLARE @CustomerIDToHandle INT
SET @CustomerIDToHandle = 1
-- as long as we have customers......
WHILE @LastCustomerID <> @CustomerIDToHandle
BEGIN
SET @LastCustomerId = @CustomerIDToHandle
-- select the next customer to handle
SELECT TOP 1 @CustomerIDToHandle = CustomerID
FROM Sales.Customer
WHERE CustomerID > @LastCustomerId
ORDER BY CustomerID
IF @CustomerIDToHandle <> @LastCustomerID
BEGIN
-- call your sproc
END
END
如果您可以将存储过程变成返回表的函数,则可以使用交叉应用。
例如,假设您有一个客户表,并且要计算他们的订单总和,您将创建一个使用CustomerID并返回总和的函数。
您可以这样做:
SELECT CustomerID, CustomerSum.Total
FROM Customers
CROSS APPLY ufn_ComputeCustomerTotal(Customers.CustomerID) AS CustomerSum
函数的外观如下:
CREATE FUNCTION ComputeCustomerTotal
(
@CustomerID INT
)
RETURNS TABLE
AS
RETURN
(
SELECT SUM(CustomerOrder.Amount) AS Total FROM CustomerOrder WHERE CustomerID = @CustomerID
)
显然,上面的示例可以在单个查询中没有用户定义的函数的情况下完成。
缺点是功能非常有限-存储过程的许多功能在用户定义的函数中不可用,并且将存储过程转换为函数并不总是有效。
我会使用可接受的答案,但是另一种可能性是使用表变量来保存一组编号的值(在这种情况下,仅是表的ID字段),并通过具有JOIN的行号遍历那些值,以达到检索循环中所需的操作。
DECLARE @RowCnt int; SET @RowCnt = 0 -- Loop Counter
-- Use a table variable to hold numbered rows containg MyTable's ID values
DECLARE @tblLoop TABLE (RowNum int IDENTITY (1, 1) Primary key NOT NULL,
ID INT )
INSERT INTO @tblLoop (ID) SELECT ID FROM MyTable
-- Vars to use within the loop
DECLARE @Code NVarChar(10); DECLARE @Name NVarChar(100);
WHILE @RowCnt < (SELECT COUNT(RowNum) FROM @tblLoop)
BEGIN
SET @RowCnt = @RowCnt + 1
-- Do what you want here with the data stored in tblLoop for the given RowNum
SELECT @Code=Code, @Name=LongName
FROM MyTable INNER JOIN @tblLoop tL on MyTable.ID=tL.ID
WHERE tl.RowNum=@RowCnt
PRINT Convert(NVarChar(10),@RowCnt) +' '+ @Code +' '+ @Name
END
对于SQL Server 2005及更高版本,您可以使用CROSS APPLY和表值函数来执行此操作。
为了清楚起见,我指的是可以将存储过程转换为表值函数的情况。
这是上述n3rds解决方案的一种变体。由于使用了MIN(),因此无需使用ORDER BY进行排序。
请记住,CustomerID(或用于进度的任何其他数字列)必须具有唯一约束。此外,为了使其尽可能快,必须在CustomerID上建立索引。
-- Declare & init
DECLARE @CustomerID INT = (SELECT MIN(CustomerID) FROM Sales.Customer); -- First ID
DECLARE @Data1 VARCHAR(200);
DECLARE @Data2 VARCHAR(200);
-- Iterate over all customers
WHILE @CustomerID IS NOT NULL
BEGIN
-- Get data based on ID
SELECT @Data1 = Data1, @Data2 = Data2
FROM Sales.Customer
WHERE [ID] = @CustomerID ;
-- call your sproc
EXEC dbo.YOURSPROC @Data1, @Data2
-- Get next customerId
SELECT @CustomerID = MIN(CustomerID)
FROM Sales.Customer
WHERE CustomerID > @CustomerId
END
我在需要检查的一些varchar上使用了这种方法,方法是先将它们放在临时表中,以为其指定ID。
这是已经提供的答案的一种变体,但是应该更好地执行,因为它不需要ORDER BY,COUNT或MIN / MAX。这种方法的唯一缺点是,您必须创建一个临时表来保存所有ID(假设您的CustomerID列表中有空白)。
也就是说,我同意@Mark Powell的观点,尽管一般而言,基于集合的方法应该更好。
DECLARE @tmp table (Id INT IDENTITY(1,1) PRIMARY KEY NOT NULL, CustomerID INT NOT NULL)
DECLARE @CustomerId INT
DECLARE @Id INT = 0
INSERT INTO @tmp SELECT CustomerId FROM Sales.Customer
WHILE (1=1)
BEGIN
SELECT @CustomerId = CustomerId, @Id = Id
FROM @tmp
WHERE Id = @Id + 1
IF @@rowcount = 0 BREAK;
-- call your sproc
EXEC dbo.YOURSPROC @CustomerId;
END
当行数很多时,我通常以这种方式进行操作:
(在较大的数据集上,我将使用上述解决方案之一)。
分隔符//
CREATE PROCEDURE setFakeUsers (OUT output VARCHAR(100))
BEGIN
-- define the last customer ID handled
DECLARE LastGameID INT;
DECLARE CurrentGameID INT;
DECLARE userID INT;
SET @LastGameID = 0;
-- define the customer ID to be handled now
SET @userID = 0;
-- select the next game to handle
SELECT @CurrentGameID = id
FROM online_games
WHERE id > LastGameID
ORDER BY id LIMIT 0,1;
-- as long as we have customers......
WHILE (@CurrentGameID IS NOT NULL)
DO
-- call your sproc
-- set the last customer handled to the one we just handled
SET @LastGameID = @CurrentGameID;
SET @CurrentGameID = NULL;
-- select the random bot
SELECT @userID = userID
FROM users
WHERE FIND_IN_SET('bot',baseInfo)
ORDER BY RAND() LIMIT 0,1;
-- update the game
UPDATE online_games SET userID = @userID WHERE id = @CurrentGameID;
-- select the next game to handle
SELECT @CurrentGameID = id
FROM online_games
WHERE id > LastGameID
ORDER BY id LIMIT 0,1;
END WHILE;
SET output = "done";
END;//
CALL setFakeUsers(@status);
SELECT @status;
如果订单很重要
--declare counter
DECLARE @CurrentRowNum BIGINT = 0;
--Iterate over all rows in [DataTable]
WHILE (1 = 1)
BEGIN
--Get next row by number of row
SELECT TOP 1 @CurrentRowNum = extendedData.RowNum
--here also you can store another values
--for following usage
--@MyVariable = extendedData.Value
FROM (
SELECT
data.*
,ROW_NUMBER() OVER(ORDER BY (SELECT 0)) RowNum
FROM [DataTable] data
) extendedData
WHERE extendedData.RowNum > @CurrentRowNum
ORDER BY extendedData.RowNum
--Exit loop if no more rows
IF @@ROWCOUNT = 0 BREAK;
--call your sproc
--EXEC dbo.YOURSPROC @MyVariable
END
我有一些生产代码,一次只能处理20名员工,下面是该代码的框架。我只是复制了生产代码并删除了下面的内容。
ALTER procedure GetEmployees
@ClientId varchar(50)
as
begin
declare @EEList table (employeeId varchar(50));
declare @EE20 table (employeeId varchar(50));
insert into @EEList select employeeId from Employee where (ClientId = @ClientId);
-- Do 20 at a time
while (select count(*) from @EEList) > 0
BEGIN
insert into @EE20 select top 20 employeeId from @EEList;
-- Call sp here
delete @EEList where employeeId in (select employeeId from @EE20)
delete @EE20;
END;
RETURN
end
我喜欢做类似的事情(尽管它仍然非常类似于使用游标)
[码]
-- Table variable to hold list of things that need looping
DECLARE @holdStuff TABLE (
id INT IDENTITY(1,1) ,
isIterated BIT DEFAULT 0 ,
someInt INT ,
someBool BIT ,
otherStuff VARCHAR(200)
)
-- Populate your @holdStuff with... stuff
INSERT INTO @holdStuff (
someInt ,
someBool ,
otherStuff
)
SELECT
1 , -- someInt - int
1 , -- someBool - bit
'I like turtles' -- otherStuff - varchar(200)
UNION ALL
SELECT
42 , -- someInt - int
0 , -- someBool - bit
'something profound' -- otherStuff - varchar(200)
-- Loop tracking variables
DECLARE @tableCount INT
SET @tableCount = (SELECT COUNT(1) FROM [@holdStuff])
DECLARE @loopCount INT
SET @loopCount = 1
-- While loop variables
DECLARE @id INT
DECLARE @someInt INT
DECLARE @someBool BIT
DECLARE @otherStuff VARCHAR(200)
-- Loop through item in @holdStuff
WHILE (@loopCount <= @tableCount)
BEGIN
-- Increment the loopCount variable
SET @loopCount = @loopCount + 1
-- Grab the top unprocessed record
SELECT TOP 1
@id = id ,
@someInt = someInt ,
@someBool = someBool ,
@otherStuff = otherStuff
FROM @holdStuff
WHERE isIterated = 0
-- Update the grabbed record to be iterated
UPDATE @holdAccounts
SET isIterated = 1
WHERE id = @id
-- Execute your stored procedure
EXEC someRandomSp @someInt, @someBool, @otherStuff
END
[/码]
请注意,你不需要身份或您的临时/变量表中的列isIterated,我只是喜欢做这种方式,所以我没有穿过绳套以删除集合上面记录着我迭代。