w3resource

PostgreSQL Create Table: Create a table to allow one of the columns of a table to contain only an auto-incremented value


11. Write a SQL statement to create a table countries including columns country_id, country_name and region_id and make sure that the column country_id will be unique and store an auto-incremented value.

Sample Solution:

Code:

CREATE TABLE IF NOT EXISTS countries ( 
COUNTRY_ID SERIAL PRIMARY KEY, 
COUNTRY_NAME varchar(40) NOT NULL, 
REGION_ID decimal(10,0) NOT NULL 
);

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Write a SQL statement to create a table named countries, including columns country_id, country_name and region_id and make sure that the country_id column will be a key field which will not contain any duplicate data at the time of insertion.
Next: Write a SQL statement to create a table countries, including country_id, country_name and region_id and make sure that the combination of columns country_id and region_id will be unique.

What is the difficulty level of this exercise?