kk Blog —— 通用基础

SELECT CASE WHEN salary <= 500 THEN '1'
	WHEN salary > 500 AND salary <= 600  THEN '2'
	WHEN salary > 600 AND salary <= 800  THEN '3'
	WHEN salary > 800 AND salary <= 1000 THEN '4'
ELSE NULL END
salary_class,  COUNT(*)  FROM    Table_A
GROUP BY CASE WHEN salary <= 500 THEN '1'
	WHEN salary > 500 AND salary <= 600  THEN '2'
	WHEN salary > 600 AND salary <= 800  THEN '3'
	WHEN salary > 800 AND salary <= 1000 THEN '4'
ELSE NULL END;

SELECT table_name, update_time FROM information_schema.tables WHERE table_schema = 'database_name' ORDER BY update_time DESC;