Update Issue

[sleezy]

l have a situation where l have two columns one for the tablename and one for the
idkey.'m trying to do an update on this table to set all the blank tabname fields = to the tablename above it
if the one below is Null .ie Tablename 'ZA02300P' and idkey '31267' should set all
the nulls on tabname where idkey in 31268,31269,31270 = 'ZA02300P'. l have 70 000 records


this is my train of thought ... need some guidance


Declare @sql nvarchar(100)
Set @sql = N'Select ExtableName_1 ,idkey + 1 From test '

EXECUTE sp_executesql @sql

BEGIN
Update test
Set tablename = Extablename
Where tablename IS NULL
AND idkey = cast(idkey AS INT) + 1
END

Update Test
Set tabname_1 =
where tablename is Null or tablename = ''




l have a situation where l have two columns one for the tablename and one for the
idkey.'m trying to do an update on this table to set all the blank tabname fields = to the tablename above it
if the one below is Null .ie Tablename 'ZA02300P' and idkey '31267' should set all
the nulls on tabname where idkey in 31268,31269,31270 = 'ZA02300P'. l have 70 000 records


----------this is what l have
If object_id('tempdb..#Test') Is not Null
Drop table #Test
Go

Create Table #Test
(
tablename Varchar(30)
,DesiredResult Varchar(30)
,Idkey int identity(1,1)
)

Insert Into #Test (tablename,DesiredResult) Values ('ADNNAM11' ,'Ok')
Insert Into #Test (tablename,DesiredResult) Values ('AH90000P','Ok' )
Insert Into #Test (tablename,DesiredResult) Values ('AH90000P','Ok')
Insert Into #Test (tablename,DesiredResult) Values ('AH90000P','Ok')
Insert Into #Test (tablename,DesiredResult) Values ('ZA02300P','Ok')
Insert Into #Test (tablename,DesiredResult) Values ('', 'Should be ZA02300P' )
Insert Into #Test (tablename,DesiredResult) Values ('', 'Should be ZA02300P')
Insert Into #Test (tablename,DesiredResult) Values ('', 'Should be ZA02300P')
Insert Into #Test (tablename,DesiredResult) Values ('ZA02300PNA','correct')
Insert Into #Test (tablename,DesiredResult) Values ('','Should be ZA02300PNA')
Insert Into #Test (tablename,DesiredResult) Values ('','Should be ZA02300PNA')
Insert Into #Test (tablename,DesiredResult) Values ('','Should be ZA02300PNA')
Insert Into #Test (tablename,DesiredResult) Values ('ADNNAM11','Ok')
Insert Into #Test (tablename,DesiredResult) Values ('ADNNAM11','Ok')
Insert Into #Test (tablename,DesiredResult) Values ('ADNNAM11','Ok')
Insert Into #Test (tablename,DesiredResult) Values ('ADNNAM11','Ok')

Select * from #test



this is my train of thought ... need some guidance


Declare @sql nvarchar(100)
Set @sql = N'Select tablename ,idkey + 1 From #test '

EXECUTE sp_executesql @sql

BEGIN
Update #test
Set tablename = tablename
Where tablename IS NULL
AND idkey = cast(idkey AS INT) + 1
END