SELECT COUNT(DISTINCT name) FROM table

What?
A quick article to remind me about this issue. Not sure whether it is specific to the Joomla Content Management System, but within the Joomla! CMS, an error 1054 comes up if you use the above statement.

Why?
The MySQL statement SELECT COUNT(DISTINCT name) FROM table is valid but I get what you mean and it's sometimes difficult to explain why you want to use it.

How?
Method #1: Add an alias to the field:
copyraw
-- Note the alias for the table (select results)
SELECT COUNT(t1.my_field) FROM (SELECT DISTINCT my_field FROM my_table) T1;

-- Performance Improvement
SELECT COUNT(1) FROM (SELECT DISTINCT my_field FROM my_table) T1;
  1.  -- Note the alias for the table (select results) 
  2.  SELECT COUNT(t1.my_field) FROM (SELECT DISTINCT my_field FROM my_table) T1; 
  3.   
  4.  -- Performance Improvement 
  5.  SELECT COUNT(1) FROM (SELECT DISTINCT my_field FROM my_table) T1; 

Method #2: Count from results (my preference):
copyraw
SELECT COUNT(my_field) FROM my_table GROUP BY my_field;
  1.  SELECT COUNT(my_field) FROM my_table GROUP BY my_field; 

Ones that didn't work for me:
Method #3: By grouping (NOT recommended for more complex queries):
SELECT COUNT(my_field) FROM my_table GROUP BY my_field;

Additional:
Not sure why method 3 is an accepted answer over the web because as soon as I put a WHERE clause in the statements and check the numbers, only method 1 and 2 return the correct number. I'm still unsure as to why WHERE...GROUP BY... doesn't return the same totals and will update this article when I figure it out.

Category: Joomla :: Article: 631

Credit where Credit is Due:


Feel free to copy, redistribute and share this information. All that we ask is that you attribute credit and possibly even a link back to this website as it really helps in our search engine rankings.

Disclaimer: Please note that the information provided on this website is intended for informational purposes only and does not represent a warranty. The opinions expressed are those of the author only. We recommend testing any solutions in a development environment before implementing them in production. The articles are based on our good faith efforts and were current at the time of writing, reflecting our practical experience in a commercial setting.

Thank you for visiting and, as always, we hope this website was of some use to you!

Kind Regards,

Joel Lipman
www.joellipman.com

Related Articles

Joes Revolver Map

Joes Word Cloud

Accreditation

Badge - Certified Zoho Creator Associate
Badge - Certified Zoho Creator Associate

Donate & Support

If you like my content, and would like to support this sharing site, feel free to donate using a method below:

Paypal:
Donate to Joel Lipman via PayPal

Bitcoin:
Donate to Joel Lipman with Bitcoin bc1qf6elrdxc968h0k673l2djc9wrpazhqtxw8qqp4

Ethereum:
Donate to Joel Lipman with Ethereum 0xb038962F3809b425D661EF5D22294Cf45E02FebF
© 2024 Joel Lipman .com. All Rights Reserved.