在没有光标的SQL Server中循环
下面是我一直在研究的一些SQL Server代码。我现在知道使用光标通常是一个坏主意，但我无法弄清楚我还能做些什么。光标的性能很糟糕。我真的只是使用一些简单的IF语句逻辑与循环，但不能将其转换为SQL。我正在使用SQL Server 2012。
IF [Last Employee] = [Employee] AND [Action] = '1-HR'
SET [Employee Record] = @counter + 1
ELSE IF [Last Employee] != [Employee] OR [Last Employee] IS NULL
SET [Employee Record] = 1
ELSE
SET [Employee Record] = @counter
基本上，如何在没有光标的情况下保持这个@counter。我觉得解决方案很简单，但我迷失了自己。谢谢你的期待。
declare curr cursor for
select WORKER, SEQUENCE, ACTION
FROM [DB].[Transactional History]
order by WORKER ,SEQUENCE asc
declare @EmployeeID as nvarchar(max);
declare @SequenceNum as nvarchar(max);
declare @LastEEID as nvarchar(max);
declare @action as nvarchar(max);
declare @currentEmpRecord int
declare @counter int;
open curr
fetch next from curr into @EmployeeID, @SequenceNum, @action;
while @@FETCH_STATUS=0
begin
if @LastEEID=@EmployeeID and @action='1-HR'
begin
set @sql = concat('update [DB].[Transactional History]
set EMPRECORD=',+ @currentEmpRecord, '+1
where WORKER=', @EmployeeID, ' and SEQUENCE=', @SequenceNum)
EXECUTE sp_executesql @sql
set @counter=@counter+1;
set @LastEEID=@EmployeeID;
set @currentEmpRecord=@currentEmpRecord+1;
end
else if @LastEEID is null or @LastEEID<>@EmployeeID
begin
set @sql = concat('update [DB].[Transactional History]
set EMPRECORD=1
where WORKER=', @EmployeeID, ' and SEQUENCE=', @SequenceNum)
EXECUTE sp_executesql @sql
set @counter=@counter+1;
set @LastEEID=@EmployeeID;
set @currentEmpRecord=1
end
else
begin
set @sql = concat('update [DB].[Transactional History]
set EMPRECORD=', @currentEmpRecord, '
where WORKER=', @EmployeeID, ' and SEQUENCE=', @SequenceNum)
EXECUTE sp_executesql @sql
set @counter=@counter+1;
end
fetch next from curr into @EmployeeID, @SequenceNum, @action;
end
close curr;
deallocate curr;
下面是构建示例表的代码。我希望每次记录为“1-HR”时增加EMPRECORD，但是为每个新的WORKER重置它。在执行此代码之前，EMPRECORD对所有记录都为null。此表显示目标输出。
CREATE TABLE [DB].[Transactional History-test](
[WORKER] [nvarchar](255) NULL,
[SOURCE] [nvarchar](50) NULL,
[TAB] [nvarchar](25) NULL,
[EFFECTIVE_DATE] [date] NULL,
[ACTION] [nvarchar](5) NULL,
[SEQUENCE] [numeric](26, 0) NULL,
[EMPRECORD] [numeric](26, 0) NULL,
[MANAGER] [nvarchar](255) NULL,
[PAYRATE] [nvarchar](20) NULL,
[SALARY_PLAN] [nvarchar](1) NULL,
[HOURLY_PLAN] [nvarchar](1) NULL,
[LAST_MANAGER] [nvarchar](255) NULL
) ON [PRIMARY]
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'1', NULL, N'EMP-Position Mgt', CAST(N'2004-01-01' AS Date), N'1-HR', CAST(1 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), N'3', N'Hourly', NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'1', NULL, N'Change Job', CAST(N'2004-05-01' AS Date), N'5-JC', CAST(2 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), N'4', NULL, NULL, NULL, N'3')
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'1', NULL, N'EMP-Terminations', CAST(N'2005-01-01' AS Date), N'6-TR', CAST(3 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), N'4', NULL, NULL, NULL, N'4')
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'1', NULL, N'Change Job', CAST(N'2010-05-01' AS Date), N'5-JC', CAST(4 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), N'3', NULL, NULL, NULL, N'4')
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'1', NULL, N'EMP-Position Mgt', CAST(N'2011-05-01' AS Date), N'1-HR', CAST(5 AS Numeric(26, 0)), CAST(2 AS Numeric(26, 0)), N'3', N'Hourly', NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'1', NULL, N'CWR-Position Mgt', CAST(N'2012-01-01' AS Date), N'1-HR', CAST(6 AS Numeric(26, 0)), CAST(3 AS Numeric(26, 0)), NULL, NULL, NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'1', NULL, N'Organizations', CAST(N'2015-01-01' AS Date), N'3-ORG', CAST(7 AS Numeric(26, 0)), CAST(3 AS Numeric(26, 0)), NULL, NULL, NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'1', NULL, N'Organizations', CAST(N'2015-01-01' AS Date), N'3-ORG', CAST(8 AS Numeric(26, 0)), CAST(3 AS Numeric(26, 0)), NULL, NULL, NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'2', NULL, N'EMP-Terminations', CAST(N'2001-01-01' AS Date), N'6-TR', CAST(9 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), NULL, NULL, NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'2', NULL, N'EMP-Terminations', CAST(N'2001-05-01' AS Date), N'6-TR', CAST(10 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), NULL, NULL, NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'2', NULL, N'Change Job', CAST(N'2004-01-01' AS Date), N'5-JC', CAST(11 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), N'3', NULL, NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'2', NULL, N'Change Job', CAST(N'2004-01-01' AS Date), N'5-JC', CAST(12 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), N'3', NULL, NULL, NULL, N'3')
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'2', NULL, N'EMP-Position Mgt', CAST(N'2014-01-01' AS Date), N'1-HR', CAST(13 AS Numeric(26, 0)), CAST(2 AS Numeric(26, 0)), N'4', N'Salary', NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'3', NULL, N'EMP-Terminations', CAST(N'2012-01-01' AS Date), N'6-TR', CAST(14 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), NULL, NULL, NULL, NULL, NULL)
GO
INSERT [DB].[Transactional History-test] ([WORKER], [SOURCE], [TAB], [EFFECTIVE_DATE], [ACTION], [SEQUENCE], [EMPRECORD], [MANAGER], [PAYRATE], [SALARY_PLAN], [HOURLY_PLAN], [LAST_MANAGER]) VALUES (N'4', NULL, N'EMP-Position Mgt', CAST(N'2012-01-01' AS Date), N'1-HR', CAST(15 AS Numeric(26, 0)), CAST(1 AS Numeric(26, 0)), NULL, NULL, NULL, NULL, NULL)
GO
select * from DB.[Transactional History-test]
4 个答案:
答案 0 :(得分：5)
这应该以更有效的方式重现光标的逻辑
WITH T
AS (SELECT *,
IIF(FIRST_VALUE([ACTION]) OVER (PARTITION BY WORKER
ORDER BY [SEQUENCE]
ROWS UNBOUNDED PRECEDING) = '1-HR', 0, 1) +
COUNT(CASE
WHEN [ACTION] = '1-HR'
THEN 1
END) OVER (PARTITION BY WORKER
ORDER BY [SEQUENCE]
ROWS UNBOUNDED PRECEDING) AS _EMPRECORD
FROM DB.[Transactional History-test])
UPDATE T
SET EMPRECORD = _EMPRECORD;
答案 1 :(得分：5)
我认为你需要的是一个带有case语句的Windows函数。这比较简单，并且应该比光标更好地执行 ，特别是如果你有好的索引。
WITH CTE
AS
(
SELECT *,
CASE WHEN [action] = '1-HR' OR [Sequence] = MIN([sequence]) OVER (PARTITION BY worker)
THEN 1 --cnter increases by 1 whether the action is 1-HR OR the sequence is the first for that worker
ELSE 0 END cnter
FROM [Transactional History-test]
)
SELECT empRecord, --can add any columns you want here
SUM(cnter) OVER (PARTITION BY worker ORDER BY [SEQUENCE]) AS new_EMPRECORD --just a cumalative sum of cnter per worker
FROM CTE
结果（我和你的比赛）：
empRecord new_EMPRECORD
--------------------------------------- -------------
1 1
1 1
1 1
1 1
2 2
3 3
3 3
3 3
1 1
1 1
1 1
1 1
2 2
1 1
1 1
答案 2 :(得分：2)
您没有指出哪个版本的TSQL - 此解决方案适用于SQL 2008转发。
根据你的光标，我对查询的猜测是：
WITH worker1hr as (select WORKER, SEQUENCE FROM [DBO].[Transactional History] WHERE Action = '1-HR')
, workerStart as (select WORKER, min(SEQUENCE) as StartSeq FROM [DBO].[Transactional History] group by worker)
SELECT th.WORKER, SEQUENCE, ACTION
, EMPRECORD
, 1 + (select count(*) from worker1hr wh WHERE wh.WORKER = th.WORKER and wh.SEQUENCE <= th.SEQUENCE
AND WH.SEQUENCE > ws.StartSeq ) as QryEmpRecord
FROM [DBO].[Transactional History] th
JOIN workerStart ws ON ws.WORKER = th.WORKER
ORDER BY WORKER ,SEQUENCE
注意：TSQL Query WITH子句需要以分号继续。奇怪，但真实......
输出：
答案 3 :(得分：0)
要使用纯SQL实现“伪游标”，可以为同一个表创建一个自连接（例如左外连接），并为左表中的每一行指定要对其执行的相应操作。右表。希望这可能有所帮助。最好的问候，
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