When dealing with data it is imperative to understand the difference between unique values and distinct values.
In the first column, we have a list of values. The values Alanis & Taylor appear more than once — there are duplicate values.
The second column contains values from the first column that only appear once. The list of values in the second column is unique — “one of a kind”.
The third column contains a list of all the values that appear in the first column but with no values repeated. It does not matter how many times the value appears in the first column; it will only appear once in the list of distinct values.
Values
| Name |
|---|
| Billie |
| Taylor |
| Sarah |
| Celine |
| Taylor |
| Alanis |
| Wendy |
| Alanis |
Unique
| Name |
|---|
| Billie |
| Sarah |
| Celine |
| Wendy |
Distinct
| Name |
|---|
| Billie |
| Taylor |
| Sarah |
| Celine |
| Alanis |
| Wendy |
Note that the values Wendy & Billie are both unique and distinct. Tayor is a distinct value, but not unique as it appears more than once in the original list.
- A value can be distinct and unique.
- A value can be distinct but not unique.
- A value that is unique will always also be distinct.
- There can never be duplicate values in a list of distinct values or a list of unique values.