SET @DBNAME = 'example';
-- requested charset 
SET @CHSET = 'utf8mb4';
-- requested collation 
SET @COLL = 'utf8mb4_general_ci'; 
-- DATABASE collation 
SELECT CONCAT('ALTER DATABASE `',@DBNAME,'` CHARACTER SET ',@CHSET,' COLLATE ',@COLL,';') as _sql UNION ALL 
-- TABLE