PostgreSQL provides us with several ways to get the day, month, and year from a date.
Three functions that immediately come to mind are; DATE_PART(), EXTRACT(), and TO_CHAR().
PostgreSQL
Install PostgreSQL on Ubuntu 20.04
Did you know that PostgreSQL is available in all Ubuntu versions by default?
Yes, that means that your Ubuntu 20.04 installation probably already has a PostgreSQL package sitting there waiting for you to install it.
And you can install it with one command, which I’ll show you below.
But what if you prefer to run the latest version of Postgres instead? Well, I’ll also show you how to install that. Installing the latest version is almost as easy as installing your local package.
Install PostgreSQL on Ubuntu 18.04
The following steps demonstrate how to install PostgresSQL on Ubuntu 18.04.
There are a couple of ways to go about installing Postgres on Ubuntu.
But before we start jumping in and installing it, did you know that by default, PostgreSQL is already available in Ubuntu 18.04?
So one option is to go right ahead and use the version that’s already included with Ubuntu.
But unless you have reason not to, you will probably want to run the latest version of PostgreSQL, in which case you’ll want to download and install the latest version.
This tutorial covers both options.
PostgreSQL Date & Time Functions
Below is a full list of date/time functions available in PostgreSQL.
PostgreSQL Math Functions
Below is a full list of mathematical functions available in PostgreSQL.
These are arranged into the following four categories:
- Mathematical Functions
- Random Functions
- Trigonometric Functions
- Hyperbolic Functions
How to Test for Overlapping Dates in PostgreSQL
In PostgreSQL, you can use the OVERLAPS operator to test for overlapping time periods.
The function returns true when two time periods (defined by their endpoints) overlap, and false when they do not overlap.
How to Format Numbers as Currency in PostgreSQL
To format a number as currency in Postgres, you can either convert it to the money data type, or use to_char() to convert it to text that includes the appropriate currency symbol.
This obviously assumes that the number isn’t already stored using the money type.
Below are examples of each of these options.
How to Pause the Execution of a Statement in PostgreSQL
PostgreSQL includes three functions that allow you to delay the execution of the server process. the execution of a statement.
In other words, you can run a statement and have it pause half way through, before continuing on its merry way.
The three functions are:
These are all very similar, but they work in slightly different ways.
Below are examples of each one.
Format the Month in Roman Numerals in PostgreSQL
In PostgreSQL, you can use the to_char() function to return dates in various formats.
One of the things you can do with this function is return the month portion of a date in roman numerals.