How next button in search works - Design problem

[Arsalan Ahmad]

Hi,

May be I am a newbie, or may be i dont have that much insight in following
systems ..i.e. why i have some confusions as below:

In many websites, when search is performed on some keywords (not only
including google which perform general search but other sites which perform
seach on a particular type of item in their database) then many search
results are obtained (for example more than 100 or even more than 1000) but
only limited amount of results are displayed in a page (like for example 10
results per page). Thus in order to display the next 10 results, a user has
to click on 'Next' button. Similarly, it is possible that a user can click
on 'Previous' button to display the previous 10 results. My question is what
are different mechanisms to perform this and which one would be most optimal
than others?

Why I am asking this question because, if we are performing a search by
sending a query of keywords to a website then we get following procedure:

Browser->Send Query->ASP.NET page(considering we are using ASP.NET although
it could be PHP or ASP or JSP etc)

Now internally from ASP.NET page, a database connection is opened (say using
ADO.NET) and search is performed by sending a query to database and getting
the results. So we get:

ASP.NET page->Send query to database (using ADO.NET)

Now database returns recordset containing more than lets say 100 records (or
1000 records)

Database->Send back 1000 records->ASP.NET page

And then ASP.NET page send 10 records to client and drop the rest. So:

ASP.NET page->Send 10 records->Client Browser.

So now when the client press Next button what happens? It seems illogical to
send same search query to database and then dropping first 10 records from
recordset and only passing recordset from 11th record to 20th records to
client browser.

So, can anyone please tell me what are different approaches to handle this.

Thanks,

Arsalan

 

[Craig Deelsnyder]

So now when the client press Next button what happens? It seems
illogical to
send same search query to database and then dropping first 10 records
from
recordset and only passing recordset from 11th record to 20th records to
client browser.

So, can anyone please tell me what are different approaches to handle
this.

Thanks,

Arsalan

usually you write your query in the sproc (or your code) to return only
those records needed. In SQL Server you could use a ROWCOUNT or use TOP
in your final SELECT statement. Dunno how other databases allow this to
happen, but I assume most do (trim resultset before returning).

The use of TOP for example, to hone in on the 11-20 for instance is a
tricky implementation. A couple references:

http://weblogs.asp.net/pwilson/archive/2003/10/10/31456.aspx
http://www.aspfaq.com/show.asp?id=2120

 

[Yama]

Hi,

Have you used paging in the past? Here is how you would do a paging query in
T-SQL:

//-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~
SELECT TOP <pageSize> *
FROM
(
SELECT TOP (<pageSize> * <pageIndex>)
< columns names>
FROM
< table name >
WHERE
< condition >
ORDER BY < PK column name > DESC
)
AS anyNameYouWant ORDER BY < PK column name > ASC
//-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~


<pageSize> = the number of records to be retrieved
<pageIndex> = the desired page index (1 based)
<column names> = list of the column names
<table name> = source table name and optional joined tables
<condition> = optional filter condition
< PK column name > = the primary key column name (it has to be also present
into the <column names> list)



Sample T-SQL for getting 5 records from the Northwind Employee table from
the second page:

//-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~
USE Northwind
SELECT TOP 5 *
FROM(
SELECT TOP 10
EmployeeID,
LastName,
FirstName,
Title,
BirthDate,
HireDate
FROM
Employees

ORDER BY EmployeeID DESC

)
AS Employees ORDER BY EmployeeID ASC
//-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~

USE Northwind

-- Page 1
SELECT TOP 3 *
FROM(
SELECT TOP 3
EmployeeID,
LastName,
FirstName,
Title,
BirthDate,
HireDate
FROM
Employees

ORDER BY EmployeeID DESC

)
AS Employees ORDER BY EmployeeID ASC

-- Page 2
SELECT TOP 3 *
FROM(
SELECT TOP 6
EmployeeID,
LastName,
FirstName,
Title,
BirthDate,
HireDate
FROM
Employees

ORDER BY EmployeeID DESC

)
AS Employees ORDER BY EmployeeID ASC

-- Page 3
SELECT TOP 3 *
FROM(
SELECT TOP 9
EmployeeID,
LastName,
FirstName,
Title,
BirthDate,
HireDate
FROM
Employees

ORDER BY EmployeeID DESC

)
AS Employees ORDER BY EmployeeID ASC

If using AJAX you could simply return the results you need depending on page
clicked using Callbacks... You'd be amazed at the speed of execution...


Hope this helps,

Yama Kamyar

 

[Cor Ligthert [MVP]]

Arsalan,

In ASPNET are for that nice solutions named Paging (as the name is for a
windforms as well).


Here a sample on our page for a webpage (there are as well for windowforms)

http://www.vb-tips.com/default.aspx?ID=5ef272ef-bfcc-4b1f-85f8-6750bb0390f8

For the others search on 'Paging"

I hope this helps,

Cor