merge a result set with a table but update according to existing values in target

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merge a result set with a table but update according to existing values in target

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Sarsoura

Posted Tuesday, November 13, 2012 10:34 AM

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Group: General Forum Members
Last Login: Wednesday, December 05, 2012 11:31 AM
Points: 74, Visits: 164

I have a table sectioninstructor
Sectionid,
Instructorid,
Instructorrole
-----------------------------------------------------------------------
Instructorrole (1 for primary instructor, 2 for secondary instructor)

Note I want to make sure that each section has only one primary instructor
i.e. if the new instructor is assigned primary role and there is already a record in the table that has the same sectionid and instructorrole =1 on inserting the new record I should change the instructorrole to 2
I will receive (a list of sectionids), instructorid, roleid I need to merge this list with the table sectioninstructor

I tried another way but I got an error message matched can’t have two updates
ALTER PROCEDURE [dbo].[usp_SectionInstructor_InsertList]
(
@SectionList nvarchar(1000),
@RoleID int,--(1 for primary and 2 for secondary)
@InstructorID int
)
AS
begin

select T.items as SectionID,
@InstructorID as instructorID,
@RoleID as InstructorROle

from
dbo.fn_SP2_Split(@SectionList,',') T

as Source

on
Target.SectionID=source.SectionID
and
Target.InstructorID=Source.SectionID

when Matched then
update
set Target.InstructorRole=@RoleID,
Target.updatedby=@updatedby

when not matched then
insert
(SectionID,
InstructorID,
InstructorRole
)
values
(Source.SectionID,
Source.InstructorID,
@RoleID
);

---the function

--splits a list to

CREATE FUNCTION [dbo].[fn_SP2_Split]
(@String nvarchar(max),
@Delimiter nchar(1)
)
returns @temptable TABLE (items nvarchar(max))
as
begin
declare @idx int
declare @slice nvarchar(250)

select @idx = 1
if len(@String)<1 or @String is null return

while @idx!= 0
begin
set @idx = charindex(@Delimiter,@String)
if @idx!=0
set @slice = left(@String,@idx - 1)
else
set @slice = @String

if(len(@slice)>0)
insert into @temptable(Items) values(@slice)

set @String = right(@String,len(@String) - @idx)
if len(@String) = 0 break
end
return
end

Post #1384193

Stewart "Arturius" Campbell

Posted Wednesday, November 14, 2012 1:52 AM

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Group: General Forum Members
Last Login: Yesterday @ 3:48 AM
Points: 3,125, Visits: 4,311

The error in the MERGE statement is encountered when one row in the target table will be addressed by more than one row in the source data set.
This imples either that the matching criterium is incorrect, or there is more than one update per record in the source dataset.

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Post #1384461

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