How do i implement an optimized paging when joining multiple tables using UNION ALL and returning only specific number of rows…
——————————————————————————————————————-
declare @startRow int
declare @PageCount int

set @startRow = 0
set @PageCount = 20

set rowcount @PageCount

select Row_Number() OVER(Order by col1) as RowNumber, col1, col2
from
(
select col1, col2 from table1 where datetimeCol between (@dateFrom and @dateTo)
union all
select col1, col2 from table2 where datetimeCol between (@dateFrom and @dateTo)
union all
select col1, col2 from table3 where datetimeCol between (@dateFrom and @dateTo)
union all
select col1, col2 from table4 where datetimeCol between (@dateFrom and @dateTo)
union all
select col1, col2 from table5 where datetimeCol between (@dateFrom and @dateTo)
) as tmpTable
where RowNumber > @startRow
——————————————————————————————————————-

table 3, 4, & 5 have huge number of row (millions of rows) where table 1 & 2 may only have few thousand rows.

If startRow is “0″, I only expect data from Row 1 to 20 (from Table1).
I’m getting the correct result but has a high overhead on the remaining table while sql server tries to all all the data and filter it….

the longer the interval of the @dateFrom and @dateTo makes my query significantly slower while trying to retrieve only few rows from the overall result set

Please help how i can implement a simple but better approach with a similar logic. :(

for example i have a recurrence schedule without an end date :

;WITH cteDate as
(
(
select event_id, summary, dt_start
from events
)
UNION ALL
(
select event_id, summary, dateadd(d,1,dt_start)
from cteDate
)
)

SELECT * FROM cteDate
order by dt_start desc
OPTION(MAXRECURSION 0)

Thanks

select Row_Number() OVER(Order by col1) as RowNumber, col1, col2
from
(
select col1, col2 from table1
union
select col1, col2 from table2
) as tmpTable
where RowNumber between 1 and 10

How this works?

First, we retrieved all the records in one or more tables and put it into a temporary table
Second, select the records from the temporary table and perform Row_Number

AND Mark Smit, SEE MY POST ABOVE (stone October 20, 2011 at 3:57 PM)
just change the query in the declare cursor keyset…that technique is far more efficient than cte when it comes to large amount of record…

NOTE: if one or both tables containing large amount of records, the query will be slower ..

If you need help and more info about it just leave a comment here.

Example – This works with one table.

With cteresult as
(Select col1,
col2,
col3,
Row_Number() OVER(Order by col1) as RowNumber
from table1)
select * from cteresult
where RowNumber between 1 and 10

Hoe can I include a union with another table, but the ordering must be across both tables.

I created a script to make the trick… (note it will take time for first run)

declare @Result table (
ACCOUNTNO varchar(20),
CONTACT varchar(40))

declare curO cursor KEYSET for
select ACCOUNTNO, CONTACT
from CONTACT
order by RecID

open curO

declare @ACCOUNTNO varchar(20)
declare @CONTACT varchar(40)

declare @PageSize int
set @PageSize = 20 — CHANGE THE DESIRED PAGE SIZE
declare @PageNo int
set @PageNo = 200– CHANGE PAGE NUMBER TO GET
declare @RecLoc int
set @RecLoc = (@PageSize * (@PageNo-1)) + 1

declare @CurrRow int
set @CurrRow = 0

fetch absolute @RecLoc from curO into @ACCOUNTNO, @CONTACT
while @@FETCH_STATUS = 0 begin
set @CurrRow = @CurrRow + 1
insert into @Result (ACCOUNTNO, CONTACT)
values (@ACCOUNTNO, @CONTACT)
if @CurrRow >= @PageSize goto g
fetch next from curO into @ACCOUNTNO, @CONTACT
end
g:
close curO
deallocate curO

select * from @Result

ENJOY!!!!!!!!
You may send email at [email removed] for questions :)

select 1 , ‘c’ , ‘d’ , ‘e’ union all
select 2 , ‘d’ , ‘e’ , ‘f’ union all
select 3 , ‘d’ , ‘f’ , ‘g’

select * from #tbl

declare @c1 varchar(100) , @c2 varchar(100) , @c3 varchar(100)
select @c1 = ” , @c2=” , @c3=”
select @c1 = @c1+c1 , @c2=@c2+c2 , @c3=@c3+c3 from #tbl
select @c1 c1 , @c2 c2 , @c3 c3

drop table #tbl

Thanks,
abhIShek onlin4all

select 1 , ‘c’ , ‘d’ , ‘e’ union all
select 2 , ‘d’ , ‘e’ , ‘f’ union all
select 3 , ‘d’ , ‘f’ , ‘g’

select * from #tbl

declare @c1 varchar(100) , @c2 varchar(100) , @c3 varchar(100)
select @c1 = ” , @c2=” , @c3=”
select @c1 = @c1+c1 , @c2=@c2+c2 , @c3=@c3+c3 from #tbl
select @c1 c1 , @c2 c2 , @c3 c3

drop table #tbl

Thanks in advance,

create table #tbl (id int , c1 varchar(10), c2 varchar(10), c3 varchar(10))
insert into #tbl

select 1 , ‘c’ , ‘d’ , ‘e’ union all
select 2 , ‘d’ , ‘e’ , ‘f’ union all
select 3 , ‘d’ , ‘f’ , ‘g’

select * from #tbl
drop table #tbl

–Result:
——————-
–| c1 | c2 |c3 |
–|—-|—–|—-|
–| cdd| def |efg |
——————-

check this out .
please ppl do let me know if there is any problem or it works for you like with me … enjoy..

Create PROCEDURE [dbo].[GetData]
(
@Pagesize int,
@Pagenumber int,
@Tablename nVarchar(50),
@ColumnList nVarchar(500),
@Orderby nVarchar(50)
)
AS
begin
Declare @FirstRow nVarchar(20)
Declare @LastRow nVarchar(20)
Declare @query nVarchar (2000)

SET @Pagenumber=@Pagenumber-1
Select @FirstRow = @Pagenumber * @Pagesize + 1,
@LastRow = @PageNumber * @PageSize + @PageSize ;

set @query =’WITH cte_Table(PageNumber,’ +@ColumnList +’ ) AS ( SELECT ROW_NUMBER() OVER (ORDER BY ‘+@Orderby+’ ASC ) AS PageNumber,’+@ColumnList+’ FROM ‘+ @Tablename+’ ) SELECT * FROM cte_Table WHERE PageNumber Between ‘+@FirstRow +’ and ‘+ @LastRow
print @query
EXEC sp_executesql @query
END

http://frugalcoder.us/post/2010/02/23/tsql-paged-result-sproc.aspx

The condition “AND row_number=21″ in WHERE clause is not clear. Can you provide the full statement?

Regards,
Pinal Dave

In the SELECT WHERE, I use: row_number>=1 AND row_number=21 AND row_number<=40, there maybe no row numbers in that range, but records do exist to be displayed.

1st record set:
1
2
4
5
7
8
13
15
19
(9) rows

2nd record set may only return 5 rows but there are many more:
21
22
24
25
28

ROW_NUMBER doesn't work as I'd anticipated, where I want to get the next 20 records and append them to the table display object.

Hopefully, that makes sense.
Mark

Great query…

Fantastic..it works perfactly…

I think u’r master of Query.. hahaha

Thank u very much… :)