How to select the nth row in a SQL database table? I'm interested in learning some (ideally) database agnostic ways of selecting the nth row from a database table. It would also be interesting to see how this can be achieved using the native functionality of the following databases: SQL Server MySQL PostgreSQL SQLite Oracle I am currently doing something like the following in SQL Server 2005, but I'd be interested in seeing other's more agnostic approaches: WITH Ordered AS ( SELECT ROW_NUMBER() OVER

SQL Group By with an Order By I have a table of tags and want to get the highest count tags from the list. Sample data looks like this id (1) tag ('night') id (2) tag ('awesome') id (3) tag ('night') using SELECT COUNT(*), `Tag` from `images-tags` GROUP BY `Tag` gets me back the data I'm looking for perfectly. However, I would like to organize it, so that the highest tag counts are first, and limit it to only send me the first

What is the difference between “INNER JOIN” and “OUTER JOIN”? Also how do LEFT JOIN, RIGHT JOIN and FULL JOIN fit in? Answer : Assuming you're joining on columns with no duplicates, which is a very common case: An inner join of A and B gives the result of A intersect B, i.e. the inner part of a Venn diagram intersection. An outer join of A and B gives the results of A union B, i.e. the outer parts of a Venn diagram union. Examples Suppose you have two tables,

Select  where  OR  Condition Is there a way to select data where any one of multiple conditions occur on the same field? Example: I would typically write a statement such as: select * from TABLE where field = 1 or field = 2 or field = 3 Is there a way to instead say something like: select * from TABLE where field = 1 || 2 || 3 Any help is appreciated. Answer: Sure thing, the simplest way is this: select foo from

Quick easy way to migrate SQLite3 to MySQL? Anyone know a quick easy way to migrate a SQLite3 database to MySQL? Answer : Here is a list of converters (not updated since 2011): http://www.sqlite.org/cvstrac/wiki?p=ConverterTools (or snapshot at archive.org) An alternative method that would work nicely but is rarely mentioned is: use an ORM class that abstracts specific database differences away for you. e.g. you get these in PHP (RedBean), Python (Django's ORM layer, Storm, SqlAlchemy), Ruby on Rails (ActiveRecord), Cocoa (CoreData) i.e. you could do this: Load

MyISAM versus InnoDB I'm working on a projects which involves a lot of database writes, I'd say (70% inserts and 30% reads). This ratio would also include updates which I consider to be one read and one write. The reads can be dirty (e.g. I don't need 100% accurate information at the time of read).The task in question will be doing over 1 million database transactions an hour. I've read a bunch of stuff on the web about the differences between MyISAM and

What is a good way to De-Normalize a mysql database? I have a large database of normalized order data that is becoming very slow to query for reporting. Many of the queries that I use in reports join five or six tables and are having to examine tens or hundreds of thousands of lines. There are lots of queries and most have been optimized as much as possible to reduce server load and increase speed. I think it's time to start keeping a