SQL SELECT UNIQUE

The SQL SELECT UNIQUE statement is used to return unique values from a column in a table. It eliminates duplicate rows from the result set. This is particularly useful when you want to retrieve distinct records without any repetition.

Syntax

The basic syntax for SELECT UNIQUE is: 

SELECT UNIQUE column_name
FROM table_name;
Note: In modern SQL, SELECT DISTINCT is used instead of SELECT UNIQUE. The functionality remains the same.

Example

Consider a table Staff with a column Department. We want to retrieve all unique departments from the table.

Code Example


-- Retrieve unique departments from the Staff table
SELECT UNIQUE Department FROM Staff;

-- Alternative syntax with DISTINCT
SELECT DISTINCT Department FROM Staff;

Output

Department
HR
IT
Finance

Explanation

- The SELECT UNIQUE Department query retrieves all unique values from the Department column.
- In this example, even if multiple employees belong to the same department, each department is listed only once in the result.
- The SELECT DISTINCT statement is equivalent to SELECT UNIQUE and is the preferred syntax in modern SQL.

Best Practices

- Use SELECT DISTINCT instead of SELECT UNIQUE for better compatibility across SQL implementations.
- Ensure that the column used in the query contains meaningful data where duplication needs to be avoided.