SQL Interview Question - Fetch Unique Values Without DISTINCT! #sqlinterview #coding

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I’ve got an SQL trick that will level up your data engineering game! 💻🚀

As someone who earned the Oracle SQL Expert 1z0-071 certification and recently published 'Mastering SQL Window Functions,' I’m always on the lookout for efficient and innovative ways to handle data. Today, I’m sharing a quick SQL trick that can fetch unique records from your database without using the DISTINCT keyword.

Imagine you need to fetch all the unique records from a column in your table. The usual approach would be to use the DISTINCT keyword. But here’s the twist—how do you achieve this without using DISTINCT, subqueries, or CTEs? 🤔

It’s simpler than you think. Use the GROUP BY clause! This groups the results by the column you want, giving you unique records effortlessly.

Fun fact: A study by Gartner reveals that effective data management, including SQL optimization, can improve decision-making efficiency by up to 33%. 🌐📊

Try it out and let me know if you knew this trick already! Comment below and share your thoughts or any other cool SQL tips you have! Let’s keep learning together. 🚀

[harinadhbabu]

Select first_name from employees
Union
Select first_name from employees;

[abhisheksinha]

select emp.first_name from
(select e.first_name, row_number() over (partition by first_name) as row_num from employees e) emp where row_num=1

[sowmya]

I knew this.But when you said not using sub query distinct or cte, got confused a while.😅

[vishal.Ugrejiya]

Without aggregate functions group by doesn't work

[aaroncode]

Which is a more efficient way to save costs?

[yeshichoedon]

Hi can I ask u something ?Did sql server can fail to pass exam?

[ranajparida]

I know before. Another techique is
SELECT a.first_name
FROM your_table_name a
LEFT JOIN your_table_name b
ON a.first_name = b.first_name AND a.rowid > b.rowid
WHERE b.first_name IS NULL;

[shekhark]

Nice trick, I've used this. But effective

[anirudh]

To fetch last second record from table.

[roshniagrawal]

i knew this, but is it cost effective ?