When I worked on the Zend Framework's database component, we tried to abstract the functionality of the LIMIT
clause supported by MySQL, PostgreSQL, and SQLite. That is, creating a query could be done this way:
$select = $db->select();
$select->from('mytable');
$select->order('somecolumn');
$select->limit(10, 20);
When the database supports LIMIT
, this produces an SQL query like the following:
SELECT * FROM mytable ORDER BY somecolumn LIMIT 10, 20
This was more complex for brands of database that don't support LIMIT
(that clause is not part of the standard SQL language, by the way). If you can generate row numbers, make the whole query a derived table, and in the outer query use BETWEEN
. This was the solution for Oracle and IBM DB2. Microsoft SQL Server 2005 has a similar row-number function, so one can write the query this way:
SELECT z2.*
FROM (
SELECT ROW_NUMBER OVER(ORDER BY id) AS zend_db_rownum, z1.*
FROM ( ...original SQL query... ) z1
) z2
WHERE z2.zend_db_rownum BETWEEN @offset+1 AND @offset+@count;
However, Microsoft SQL Server 2000 doesn't have the ROW_NUMBER()
function.
So my question is, can you come up with a way to emulate the LIMIT
functionality in Microsoft SQL Server 2000, solely using SQL? Without using cursors or T-SQL or a stored procedure. It has to support both arguments for LIMIT
, both count and offset. Solutions using a temporary table are also not acceptable.
Edit:
The most common solution for MS SQL Server 2000 seems to be like the one below, for example to get rows 50 through 75:
SELECT TOP 25 *
FROM (
SELECT TOP 75 *
FROM table
ORDER BY BY field ASC
) a
ORDER BY field DESC;
However, this doesn't work if the total result set is, say 60 rows. The inner query returns 60 rows because that's in the top 75. Then the outer query returns rows 35-60, which doesn't fit in the desired "page" of 50-75. Basically, this solution works unless you need the last "page" of a result set that doesn't happen to be a multiple of the page size.
Edit:
Another solution works better, but only if you can assume the result set includes a column that is unique:
SELECT TOP n *
FROM tablename
WHERE key NOT IN (
SELECT TOP x key
FROM tablename
ORDER BY key
);
Conclusion:
No general-purpose solution seems to exist for emulating LIMIT
in MS SQL Server 2000. A good solution exists if you can use the ROW_NUMBER()
function in MS SQL Server 2005.