How does MySQL process ORDER BY and LIMIT in a query?

mysql sql sql-order-by sql-limit
Alex picture Alex · Jan 17, 2011 · Viewed 523.4k times · Source

I have a query that looks like this:

SELECT article FROM table1 ORDER BY publish_date LIMIT 20

How does ORDER BY work? Will it order all records, then get the first 20, or will it get 20 records and order them by the publish_date field?

If it's the last one, you're not guaranteed to really get the most recent 20 articles.

Answer

James picture James · Jan 17, 2011

It will order first, then get the first 20. A database will also process anything in the WHERE clause before ORDER BY.

Related questions

MySQL "Group By" and "Order By"

I want to be able to select a bunch of rows from a table of e-mails and group them by the from sender. My query looks like this: SELECT `timestamp`, `fromEmail`, `subject` FROM `incomingEmails` GROUP BY LOWER(`fromEmail`) ORDER BY `…

Read More
SQL order string as number

I have numbers saved as VARCHAR to a MySQL database. I can not make them INT due to some other depending circumstances. It is taking them as character not as number while sorting. In database I have 1 2 3 4 5 6 7 8 9 10... On my page …

Read More
Using union and order by clause in mysql

I want to use order by with union in mysql query. I am fetching different types of record based on different criteria from a table based on distance for a search on my site. The first select query returns data …

Read More