In the world of SQL Server, there are often multiple ways to achieve the same result. This can sometimes lead to confusion, especially when it comes to syntax that appears to be similar. In this article, we will explore the difference between SQL SELECT UNIQUE and SELECT DISTINCT statements.

Both SELECT UNIQUE and SELECT DISTINCT are used to retrieve unique values from a column that may contain duplicates. The purpose of these statements is to eliminate duplicate entries and display only the unique values.

Let’s start by discussing the SELECT UNIQUE statement. It is important to note that SELECT UNIQUE is not an ANSI standard SQL statement and is specific to the Oracle database system. The syntax for using SELECT UNIQUE in Oracle is as follows:

SELECT UNIQUE column FROM table;

Here, “column” refers to the name of the column from which you want to fetch unique values, and “table” is the name of the table on which the query is being executed.

On the other hand, the SELECT DISTINCT statement is an ANSI standard SQL statement that can be used in multiple database systems, including SQL Server. The syntax for using SELECT DISTINCT is as follows:

SELECT DISTINCT column FROM table;

Just like with SELECT UNIQUE, “column” refers to the name of the column from which you want to fetch unique values, and “table” is the name of the table on which the query is being executed.

Now, let’s consider a use case to better understand the difference between these two statements. Suppose we have a table named “Person” with columns “ID”, “Name”, and “City”. The “Name” and “City” columns may contain duplicate values.

If we were to run the SELECT UNIQUE statement on the “Name” column, it would return only the unique names, ignoring any duplicate entries. Similarly, running the SELECT UNIQUE statement on the “City” column would return only the unique city names.

On the other hand, if we were to run the SELECT DISTINCT statement on the same columns, we would get the same result. Both statements behave in the same way and return the same output.

It is worth noting that while SELECT UNIQUE is specific to the Oracle database system, SELECT DISTINCT is a more widely supported syntax that can be used in various database systems, including SQL Server.

In conclusion, both SQL SELECT UNIQUE and SELECT DISTINCT statements serve the same purpose of retrieving unique values from a column. However, SELECT UNIQUE is specific to the Oracle database system, while SELECT DISTINCT is an ANSI standard SQL statement that can be used in multiple database systems. Understanding the difference between these two statements can help you write more efficient and portable SQL queries.

Thank you for reading this article. We hope you found it informative and helpful. If you have any feedback or questions, please leave a comment below.