问题
From this answer: Is there a way to loop through a table variable in TSQL without using a cursor?
I'm using the method
WHILE EXISTS(SELECT * FROM #Temp)
The problem is that it's outputting multiple tables, if possible I'd like to output as a single table.
Declare @Id int
WHILE EXISTS(SELECT * FROM #Temp)
Begin
Select Top 1 @Id = Id From #Temp
--Do some processing here
Delete #Temp Where Id = @Id
End
So right now it outputs this:
x y
-- --
1 a
x y
-- --
1 b
But I'd like it to output this:
x y
-- --
1 a
2 b
What I'm trying to achieve, I have this in a field:
1234,1432,1235
I have a process that splits the field into records(it works with sql server 2000):
DECLARE @String VARCHAR(100)
SELECT @String = str FROM field --with the 1234,1432,1235
SELECT SUBSTRING(',' + @String + ',', Number + 1,
CHARINDEX(',', ',' + @String + ',', Number + 1) - Number -1)AS str
INTO #temp
FROM master..spt_values
WHERE Type = 'P'
AND Number <= LEN(',' + @String + ',') - 1
AND SUBSTRING(',' + @String + ',', Number, 1) = ','
GO
So now, #temp has:
str
---
1234
1432
1235
So I need to go through each record to query the information I need.
And I'd like it to output something like this:
str name age
--- ---- ---
1234 Bob 23
1432 Jay 41
1235 Tim 12
The current While loop outputs it like this, which I don't want:
str name age
--- ---- ---
1234 Bob 23
str name age
--- ---- ---
1432 Jay 41
str name age
--- ---- ---
1235 Tim 12
Final Working Result:
SET NOCOUNT ON;
DECLARE @String VARCHAR(1000);
SELECT @String = Tnn FROM (SELECT
CO.USER_2 AS Tnn
FROM
[VMFG].[dbo].[CUSTOMER_ORDER] AS CO
LEFT JOIN DBO.Tnn_Header AS Tnn ON Tnn.TnnNumber = CO.USER_2 AND Tnn.StatusID = '5' WHERE CO.ID = 'ORDERID') AS Place --with the 1234,1432,1235
DECLARE @Id nvarchar(50),
@Discount nvarchar(50),
@Spin nvarchar(50),
@Commission_Hmm nvarchar(50),
@Commission nvarchar(50),
@TnnID nvarchar(50);
DECLARE @Output TABLE (
TnnNumber nvarchar(50),
Discount nvarchar(50),
Spin nvarchar(50),
Commission_Hmm nvarchar(50),
Commission nvarchar(50),
TnnID nvarchar(50));
DECLARE crs CURSOR STATIC LOCAL READ_ONLY FORWARD_ONLY
FOR SELECT SUBSTRING(',' + @String + ',', Number + 1,
CHARINDEX(',', ',' + @String + ',', Number + 1) - Number -1) AS [ID]
FROM master..spt_values
WHERE Type = 'P'
AND Number <= LEN(',' + @String + ',') - 1
AND SUBSTRING(',' + @String + ',', Number, 1) = ',';
OPEN crs;
FETCH NEXT
FROM crs
INTO @Id;
WHILE (@@FETCH_STATUS = 0)
BEGIN
-- do some processing..
SELECT
@Id = TH.TnnNumber,
@Discount = CASE WHEN COUNT(DISTINCT TL.DiscountCodeID) > 1 THEN 'Varies, View Tnn' ELSE CAST(MAX(DC.Value) AS VARCHAR(60)) END,
@Spin = CASE WHEN TS.SpinID > 4 THEN 'Has Specifics, View Tnn' ELSE TS.Value END,
@Commission_Hmm = CASE WHEN COUNT(DISTINCT TL.Commission_Hmm) > 1 THEN 'Varies, View Tnn' ELSE CAST(MAX( ISNULL(str(TL.Commission_Hmm,12),'Default Comm')) AS VARCHAR(60)) END,
@Commission = CASE WHEN COUNT(DISTINCT TL.Commission) > 1 THEN 'Varies, View Tnn' ELSE CAST(MAX(ISNULL(str(TL.Commission,12),'Default Comm')) AS VARCHAR(60)) END,
@TnnID = TL.TnnID
FROM DBO.Tnn_Header AS TH
LEFT JOIN DBO.Tnn_LINE AS TL ON TH.TnnID = TL.TnnID
LEFT JOIN DBO.Tnn_Spin AS TS ON TH.SpinID = TS.SpinID
LEFT JOIN DBO.Tnn_DiscountCode AS DC ON TL.DiscountCodeID = DC.DiscountCodeID
WHERE TnnNumber = @id
GROUP BY
TH.TnnNumber,
TS.SpinID,
TS.Value,
TL.TnnID
-- end do some processing..
INSERT INTO @Output (TnnNumber, Discount, Spin, Commission_Hmm, Commission, TnnID)
VALUES (@Id, @Discount, @Spin, @Commission_Hmm, @Commission, @TnnID);
FETCH NEXT
FROM crs
INTO @Id;
END;
CLOSE crs;
DEALLOCATE crs;
SELECT TnnNumber, Discount, Spin, Commission_Hmm, Commission, TnnID
FROM @Output;
回答1:
You are wasting your time and energy following such bad advice. If you absolutely must (extra emphasis on the must) take a row-by-row approach (CURSOR or WHILE loop), then you are better off with a CURSOR. It is a built-in construct that is more efficient, and less error-prone. You just need to use the right options, such as making it STATIC, LOCAL, READ_ONLY, and FORWARD_ONLY. You don't need STATIC if the cursor query is only hitting temporary tables and/or table variables.
People will argue with this and say that "you must avoid cursors at all cost!", but they haven't done the tests to see that such a popular notion is really just a myth. And if they have done tests that appear to confirm it, then they haven't set the appropriate options, mostly STATIC, which dumps the result of the cursor query into a temp table. Without this option, fetching new rows will re-check the base tables to make sure that they still exist, and that is where the performance hit is (the I/O plus the locking). And that is also why you typically don't need the STATIC option when querying only temporary tables and/or table variables. What do I mean by "re-checking"? Just look at the documentation for @@FETCH_STATUS. The return values don't just cover "success" (0) and "no more rows" (-1): there is a return value, (-2), that means "The row fetched is missing".
SET NOCOUNT ON;
DECLARE @Id INT,
@Name sysname,
@Type VARCHAR(5);
-- the Table Variable replaces #Temp2 in the original query
DECLARE @Output TABLE (Id INT NOT NULL, Name sysname, [Type] VARCHAR(5));
-- the CURSOR replaces #Temp in the original query
DECLARE crs CURSOR STATIC LOCAL READ_ONLY FORWARD_ONLY
FOR SELECT [object_id], name, [type]
FROM sys.objects -- dbo.sysobjects for SQL 2000 -- ATable in the original query
ORDER BY [object_id] ASC;
OPEN crs;
FETCH NEXT
FROM crs
INTO @Id, @Name, @Type;
WHILE (@@FETCH_STATUS = 0)
BEGIN
INSERT INTO @Output (Id, Name, [Type])
VALUES (@Id, @Name, @Type);
-- do some processing..
FETCH NEXT -- replaces the DELETE and re-SELECT in the original query
FROM crs
INTO @Id, @Name, @Type;
END;
CLOSE crs;
DEALLOCATE crs;
SELECT Id, Name, [Type]
FROM @Output;
UPDATE
Given the iteration is being done over a query that splits a CSV of INTs, the resulting query would look similar to the following:
SET NOCOUNT ON;
DECLARE @String VARCHAR(1000);
SELECT @String = str FROM [Table]; --with the 1234,1432,1235
DECLARE @Id INT,
@Name NVARCHAR(50),
@Age TINYINT;
DECLARE @Output TABLE (Id INT NOT NULL, Name NVARCHAR(50), Age TINYINT);
DECLARE crs CURSOR STATIC LOCAL READ_ONLY FORWARD_ONLY
FOR SELECT SUBSTRING(',' + @String + ',', Number + 1,
CHARINDEX(',', ',' + @String + ',', Number + 1) - Number -1) AS [ID]
FROM master..spt_values
WHERE Type = 'P'
AND Number <= LEN(',' + @String + ',') - 1
AND SUBSTRING(',' + @String + ',', Number, 1) = ',';
OPEN crs;
FETCH NEXT
FROM crs
INTO @Id;
WHILE (@@FETCH_STATUS = 0)
BEGIN
-- do some processing..
-- Logic to set value of @Name
-- Logic to set value of @Age
INSERT INTO @Output (Id, Name, Age)
VALUES (@Id, @Name, @Age);
FETCH NEXT
FROM crs
INTO @Id;
END;
CLOSE crs;
DEALLOCATE crs;
SELECT Id, Name, Age
FROM @Output;
回答2:
your query has syntax error but I tried below query and worked fine
-- this is only to populate my data table
Select object_id Id, name Into #Temp From sys.tables
select * into #temp2 from #Temp where 1=2
Declare @Id int
WHILE EXISTS(SELECT * FROM #Temp)
Begin
Select Top 1 @Id = Id
From #Temp
ORDER BY Id -- this order is important
-- use insert...into, NOT select...into
insert into #temp2
select *
from #Temp
where Id = @Id
Delete #Temp Where Id = @Id
End
BTW, you can not have SELECT...INTO inside a loop, as the 2nd iteration will raise error. You need to create #temp2, out side the loop and use INSERT...INTO instead of SELECT...INTO
来源：https://stackoverflow.com/questions/35470618/sql-server-how-to-output-one-table-result-from-multiple-results-with-a-while-que