Mastering the Art of Eliminating Duplicates: The Key Differences between Oracle SQL`s Distinct and Unique (With Practical Code Illustrations)

Table of content

  1. Introduction
  2. Understanding Duplicates in Oracle SQL
  3. Oracle SQL's DISTINCT Keyword
  4. Oracle SQL's UNIQUE Keyword
  5. Practical Code Illustrations of DISTINCT and UNIQUE
  6. Key Differences between DISTINCT and UNIQUE
  7. Best Practices for Eliminating Duplicates
  8. Conclusion


Hey there! Are you tired of dealing with duplicate data in your Oracle SQL database? Me too! That's why I wanted to share some nifty tips and tricks I've learned for mastering the art of eliminating duplicates. Specifically, we'll be diving into the key differences between Oracle SQL's Distinct and Unique.

I know what you're thinking, "Distict and Unique, aren't they the same thing?" Not exactly! While they both are used to remove duplicates, there are important distinctions (pun intended) between the two. But don't worry, I'll walk you through each one and provide practical code illustrations to help solidify your understanding.

By the end of this article, not only will you know the difference between Distinct and Unique, but you'll also have a deeper understanding of how Oracle SQL operates. How amazingd it be to confidently navigate your database and eliminate duplicates like a pro? Let's get started!

Understanding Duplicates in Oracle SQL

can be a bit tricky, but fear not my fellow SQL lovers! Duplicates are essentially repeated data values in a table that shouldn't be there, and they can mess up your query results. So, how do we find and eliminate them? That's where the nifty tools of DISTINCT and UNIQUE come into play.

Distinct and Unique do pretty much the same thing, but there are some key differences that are important to understand. DISTINCT removes duplicates from the result set of a SELECT query, which means it only returns distinct (i.e., unique) values. On the other hand, UNIQUE is a constraint that can be added to a column or combination of columns to ensure that no duplicates are inserted into the table.

Now, how amazingd it be if you could use these tools to eliminate pesky duplicates from your Oracle SQL database with ease? Well, you can! With a little bit of practice and know-how, you'll be eliminating duplicates like a pro in no time. Stay tuned for more tips and tricks on mastering the art of eliminating duplicates with Oracle SQL's DISTINCT and UNIQUE commands.

Oracle SQL’s DISTINCT Keyword

Alright, let's talk about – one of the most nifty tricks to help you eliminate duplicate values in your queries. So, what exactly does DISTINCT do? Well, it filters out the duplicates from a query result, returning only one instance of each unique value selected. It's like magic – you can get rid of doubles and present only the finest bits of data for your analysis.

Here's a quick example to help you understand how DISTINCT works. Suppose we have a table called "students", which contains fields such as "student_id", "name", "age", and "address". If we want to find out the unique ages of our students, we can use the SELECT query with the DISTINCT keyword like this:


And voila! We'll have a list of all unique ages of our students without duplicates. It's as simple as that. How amazing is it that just one keyword can make our lives so much easier?

Of course, there are some limitations to using DISTINCT, such as if you want to include other fields in your query that are not part of the DISTINCT selection – but don't worry, there are ways around this that we will explore later. For now, just remember that the DISTINCT keyword is your friend when it comes to eliminating duplicates in your SQL queries.

Oracle SQL’s UNIQUE Keyword

Let's talk about . It's a nifty little keyword that ensures that all the values in a column are unique. That means you won't have any duplicate values in your results when you execute your query. How amazing is that?!

So, why use the UNIQUE keyword instead of DISTINCT? Well, DISTINCT eliminates duplicate rows from your result set, while UNIQUE only ensures that there are no duplicate values in a single column. So, if you only want to make sure that there are no repeating values in one column, use UNIQUE.

Here's an example query that uses the UNIQUE keyword:

SELECT UNIQUE department_name
FROM employees;

This query will return a list of all unique department names in the employees table. If there are any duplicates, they will be eliminated.

One thing to note is that the UNIQUE keyword is synonymous with the keyword DISTINCTROW. So, you can use either keyword in your query and get the same results.

In summary, the UNIQUE keyword is a handy tool to ensure that there are no duplicate values in a single column. Use it when you only want to eliminate duplicates in one specific column, and use DISTINCT when you want to eliminate duplicate rows from your result set. Happy querying!

Practical Code Illustrations of DISTINCT and UNIQUE

Okay, folks! It's time to get our hands dirty with some in Oracle SQL. This is where the rubber meets the road, and we can really see how these two commands work in action.

Let's start with DISTINCT, shall we? Imagine we have a table called "employees" with columns for "employee_id," "first_name," "last_name," and "department." We want to retrieve a list of all the departments in the company without any duplicates. Here's how we would do it:

FROM employees;

Boom! That's it. The DISTINCT keyword tells Oracle SQL to eliminate any duplicates in the "department" column and only show us unique values. Nifty, huh?

But what if we wanted to find all the unique combinations of first and last names in the table? This is where UNIQUE comes in. Unlike DISTINCT, UNIQUE works across multiple columns. Here's how we would use it:

SELECT UNIQUE first_name, last_name
FROM employees;

Wow, how amazingd it be? The UNIQUE keyword tells Oracle SQL to look for all combinations of "first_name" and "last_name" in the table and only show us the ones that are unique. It's like a supercharged version of DISTINCT!

So there you have it, folks. This is just the tip of the iceberg when it comes to using DISTINCT and UNIQUE in Oracle SQL, but these practical code illustrations should give you a good starting point for mastering the art of eliminating duplicates. Happy coding!

Key Differences between DISTINCT and UNIQUE

So you want to master the art of eliminating duplicates in Oracle SQL? Great choice! But first, let's delve into the .

Now, you might be thinking, "Wait a minute, aren't they the same thing?" Well, not exactly. DISTINCT and UNIQUE both serve the purpose of reducing duplicates in a result set, but they do so in slightly different ways.

DISTINCT is a keyword that you can use in your SELECT statement. It tells Oracle to return only distinct values for a specified column or set of columns. For example, if you have a table of customer orders and you want to see a list of unique customer names, you could use the following SQL statement:

SELECT DISTINCT customer_name FROM orders;

On the other hand, UNIQUE is a constraint that you can add to a column when you create a table. It tells Oracle to ensure that all values in that column are unique. This means that if you try to insert a value that already exists in that column, you will get an error. Here's an example of how you could create a table with a UNIQUE constraint:

CREATE TABLE employees (
  employee_id NUMBER(5) PRIMARY KEY,
  employee_email VARCHAR2(50) UNIQUE,
  employee_name VARCHAR2(50)

So, to sum up: DISTINCT helps you eliminate duplicates from a result set, while UNIQUE ensures that you can't insert duplicate values into a column.

Knowing the difference between these two nifty little keywords can make a world of difference in your SQL queries. How amazingd it be to impress your boss with your newfound Oracle knowledge? Keep practicing and soon you'll be an SQL superstar!

Best Practices for Eliminating Duplicates

Alright, friend, let's talk about the best practices when eliminating duplicates in your Oracle SQL database. Trust me, you don't want to end up with a bunch of redundant data cluttering up your tables. So, here are a few tips to help you clean things up and streamline your database.

First things first, make sure you're using the right tool for the job. As we discussed in the main article, Oracle SQL offers two options: DISTINCT and UNIQUE. While they may seem similar, there are important differences to consider depending on your specific needs. Take a minute to review and choose wisely.

Once you've selected your weapon of choice, it's time to get down to brass tacks. When it comes to actually eliminating duplicates, there are a few key things to keep in mind. One nifty trick is to use the GROUP BY clause along with your chosen tool. This allows you to group together similar rows of data and effectively distill them down to their unique essence. How amazingd it be if we could do that with all the people we encounter in life, am I right?

Another good practice to follow is to keep an eye on efficiency. Depending on the size and complexity of your database, eliminating duplicates can be a time-consuming process. You'll want to optimize your queries and limit the amount of data you're working with wherever possible. This could mean filtering by specific columns or using other conditions to narrow down your results before applying DISTINCT or UNIQUE.

Lastly, and perhaps most importantly, don't be afraid to experiment! Every database is unique, and what works best for one may not work as well for another. Don't be afraid to try out different techniques, tweak your queries and see what kind of results you get. With a little patience and practice, you'll soon be a master of duplicate elimination in no time!



And there you have it, folks! We've learned all about the key differences between Oracle SQL's Distinct and Unique. With all these insights, you can now confidently eliminate duplicates from your database without hassle. Remember, the key takeaway is that DISTINCT applies to columns, while UNIQUE applies to constraints. Always double-check your code and use the appropriate query to achieve the results you want.

I hope this article has been helpful to you. Learning SQL can be intimidating, but with a little bit of practice and perseverance, you'll soon find that you're a master at it! Keep exploring and experimenting with the queries – who knows how amazing it will be when you come up with nifty solutions that will wow your team and impress your bosses.

Thank you for reading, and happy data crunching!

As a senior DevOps Engineer, I possess extensive experience in cloud-native technologies. With my knowledge of the latest DevOps tools and technologies, I can assist your organization in growing and thriving. I am passionate about learning about modern technologies on a daily basis. My area of expertise includes, but is not limited to, Linux, Solaris, and Windows Servers, as well as Docker, K8s (AKS), Jenkins, Azure DevOps, AWS, Azure, Git, GitHub, Terraform, Ansible, Prometheus, Grafana, and Bash.

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