Retrieve the Top N records from a DataBase Table?

Returning TOP N Records

Returning only the first N records in a SQL query differs quite a bit between database platforms. Here's some samples:

Microsoft SQL Server
SELECT TOP 10 column FROM table

PostgreSQL and MySQL
SELECT column FROM table
LIMIT 10

Oracle
SELECT column FROM table
WHERE ROWNUM <= 10

Sybase
SET rowcount 10
SELECT column FROM table

Firebird
SELECT FIRST 10 column
FROM table

Due to these differences if you want to keep your code database independent you should use the maxrows attribute in the cfquery tag in ColdFusion. The tradeoffs to database independance is performance, I would expect maxrows to be slower than specifying the rows in the SQL.


SELECT column FROM table

PostgreSQL and MySQL have a cool feature that will let you return an arbitrary range of rows (eg return rows 10-20). This is very handy for displaying pages of records:

SELECT column FROM table
LIMIT 10 OFFSET 20
The above query will return rows 20-30




courtesy :http://www.petefreitag.com/item/59.cfm