When using ORDER BY "column" in PostgreSQL, NULL values will come last. When using ORDER BY "column" DESC, NULLs will...

There is no such thing as a "default order" of rows in database tables. For instance, when you paginate a...

When you want to UPDATE a table with information from an associated table, you can JOIN the associated table into...

Several Rails migration methods accept index: true as an option to create an index. In some cases (like #add_column...

It's generally not trivial to change a datetime's seconds, minutes, etc in SQL. Here is how it works...

Good article about window functions. Also note how they use a postgres feature called common table expressions.

The linked article explains how to get a database-wide lock without creating table rows: This article explains how I...

Postgres 9.4 introduces a new column type: jsonb. json and jsonb columns store data differently, so just compare the two...

Sequel is an awesome ORM such as ActiveRecord. The linked article describes how easily you can implement and use materialized...

In the tradition of our PostgreSQL cheat sheet for MySQL lamers, here is a cheat sheet for Jasmine when you...

A CLI for working with Postgres databases. Ships with auto-completion and syntax highlighting.

Rails guide that covers PostgreSQL-specific column types and usages for Active Record. You should especially keep in mind the...

SELECT enum_range(NULL::portal) # Returns an array of all possible values SELECT unnest(enum_range(NULL::portal)) # Unnests the...

class Document < ActiveRecord::Base scope :any_tags, -> (tags){ where('tags && ARRAY[?]', tags) } scope :all_tags, -> (tags){ where('tags @> ARRAY...

If you get an error like this: An error occurred while installing pg (0.17.1), and Bundler cannot continue.

By default, Rails' validates_uniqueness_of does not consider "username" and "USERNAME" to be a collision. If you use MySQL...

Like in any language, a FLOAT will eventually corrupt data due to rounding errors. Please use DECIMAL, which has well...

When writing Rails migrations to convert a string column to an integer you'd usually say: change_column :table_name...

There may be reasons to change the locale of your Postgres cluster. A popular one is your development system's...

So you're switching to PostgreSQL from MySQL? Here is some help... General hints on PostgreSQL \? opens the command overview...

Rails gives you migrations to change your database schema with simple commands like add_column or update. Unfortunately these commands...

Rails understands a :limit options when you create columns in a migration. Its meaning depends on the column type, and...

validates_uniqueness_of is not sufficient to ensure the uniqueness of a value. The reason for this is that in...

For string columns, MySQL indexes the left side of a string. That means an index can speed a like query...