SQL SELECT DISTINCT Statement
The SELECT DISTINCT statement in SQL is used to return unique values from a specified column or combination of columns in a table. It eliminates duplicate records and displays only unique values.
Here is the basic syntax for the SELECT DISTINCT statement:
SELECT DISTINCT column1, column2, ...
FROM table_name;
Example Table
Let's assume we have the following table named Employees:
| ID |
Name |
Department |
| 1 |
John |
Sales |
| 2 |
Jane |
Marketing |
| 3 |
John |
Sales |
| 4 |
Alice |
HR |
| 5 |
Bob |
Sales |
| 6 |
Jane |
Marketing |
Query to Get Unique Departments
To get a list of unique departments from the Employees table, you can use the following query:
SELECT DISTINCT Department
FROM Employees;
Output:
| Department |
| Sales |
| Marketing |
| HR |
Query to Get Unique Names
To get a list of unique names from the Employees table, you can use the following query:
SELECT DISTINCT Name
FROM Employees;
Output:
Query to Get Unique Combinations of Name and Department
To get a list of unique combinations of names and departments, you can use the following query:
SELECT DISTINCT Name, Department
FROM Employees;
Output:
| Name |
Department |
| John |
Sales |
| Jane |
Marketing |
| Alice |
HR |
| Bob |
Sales |
In this example, the SELECT DISTINCT statement ensures that only unique combinations of Name and Department are returned.