[ADD] Composite index

Author: stivenramireza

classes/13-composite-index.sql

@@ -0,0 +1,9 @@
+SELECT *
+FROM city
+WHERE name = 'Jinzhou'
+AND countrycode = 'CHN'
+AND district = 'Liaoning';
+
+CREATE UNIQUE INDEX "unique_name_countrycode_district" ON city (name, countrycode, district);
+
+CREATE INDEX "district" ON city (district);