- PostgreSQL Tutorial
- Database
-
PostgreSQL Syntax
- PostgreSQL Operators
- PostgreSQL SELECT
- PostgreSQL
- PostgreSQL WHERE
- PostgreSQL ORDER BY
- PostgreSQL LIMIT
- PostgreSQL MIN and MAX
- PostgreSQL COUNT
- PostgreSQL SUM
- PostgreSQL AVG
- PostgreSQL LIKE
- PostgreSQL IN
- PostgreSQL BETWEEN
- PostgreSQL AS
- PostgreSQL Joins
- PostgreSQL INNER JOIN
- PostgreSQL LEFT JOIN
- PostgreSQL RIGHT JOIN
- PostgreSQL FULL JOIN
- PostgreSQL CROSS JOIN
- PostgreSQL UNION
- PostgreSQL GROUP BY
- PostgreSQL HAVING
- PostgreSQL EXISTS
- PostgreSQL ANY
- PostgreSQL ALL
- PostgreSQL CASE
- Exercises
PostgreSQL SELECT DISTINCT
The SELECT DISTINCT Statement
The SELECT DISTINCT statement is used to return only distinct (different) values.
Inside a table, a column often contains many duplicate values and sometimes you only want to list the different (distinct) values.
Example
Select only the DISTINCT values from the country column in the customers table:
SELECT DISTINCT country FROM customers;
Run Example »
Even though the customers table has 91 records, it only has 21 different countries, and that is what you get as a result when executing the SELECT DISTINCT statement above
SELECT COUNT(DISTINCT)
We can also use the DISTINCT keyword in combination with the COUNT statement, which in the example below will return the number of different countries there are in the customers table.
Example
Return the number of different countries there are in the customers table:
SELECT COUNT(DISTINCT country) FROM customers;
Run Example »
PostgreSQL Exercises
截取页面反馈部分，让我们更快修复内容！也可以直接跳过填写反馈内容!