UNION and CONCAT
Date: April 26th 2016
Last updated: April 26th 2016
UNION can join the results from multiple select statements, while CONCAT joins similar datatypes together. The following example was adapted from a challenge set on https://www.hackerrank.com/.
SELECT CONCAT(name, '(', SUBSTR(country, 1, 1), ')') FROM (SELECT name, country FROM my_world_table ORDER BY name) a UNION SELECT CONCAT('There are ',b.co,' people present from ',b.country) FROM (SELECT country, count(country) AS co FROM occupations GROUP BY country ORDER BY co, country) b ; /* Abby(A) Harry(A) Ray(N) Richard(N) Miles(N) There are 2 people present from Australia There are 3 people present from New Zealand