Below is some SQL Server code I have been working on. I know now that using a cursor is a bad idea in general, but I cannot figure out how else I can make this work. The performance is terrible with the cursor. I'm really just using some simple IF statement logic with a loop, but can't translate it to SQL. I'm using 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
Basically, how can I keep this @counter going without a cursor. I feel like the solution is simple, but I've lost myself. Thanks for looking.
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;
Below is code to build a sample table. I want to increase EMPRECORD every time a record is '1-HR', but reset it for each new WORKER. Before this code is executed, EMPRECORD is null for all records. This table shows the target output.
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]
Always confusing thing is which one is better; SQL While loop or cursor? While SQL While loop is quicker than a cursor, reason found that cursor is defined by DECLARE CURSOR. Every emphasis of the loop will be executed inside system memory and consuming required server assets.
This should reproduce the logic of the cursor in a more efficient way
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;
I think what you need is a Windows function with a case statement. This is simpler and should perform significantly better than your cursor especially if you have good indexes.
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
Results(mine matches yours):
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
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