first commit

data/migrations/20200207155645_countries.js

@@ -0,0 +1,13 @@
+exports.up = function(knex, Promise) {
+    return knex.schema.createTable('countries', function(countries) {
+      countries.increments();
+      countries
+        .string('name', 128)
+        .notNullable()
+        .unique();
+    });
+  };
+  
+  exports.down = function(knex, Promise) {
+    return knex.schema.dropTableIfExists('countries');
+  };

data/migrations/20200207160031_cities.js

@@ -0,0 +1,20 @@
+exports.up = function(knex) {
+    return knex.schema.createTable('cities', function(cities) {
+      cities.increments();
+
+      cities.string('name', 128).notNullable();
+      cities
+        .integer('country_id')
+        .unsigned()
+        .notNullable()
+        .references('id')
+        .inTable('countries')
+        .onDelete('CASCADE')
+        .onUpdate('CASCADE');
+    });
+  };
+  
+  exports.down = function(knex) {
+    return knex.schema.dropTableIfExists('cities');
+  };
+  

data/migrations/20200207160304_roads.js

@@ -0,0 +1,32 @@
+exports.up = function(knex) {
+    return knex.schema.createTable('roads', function(roads) {
+        roads.increments();
+
+        roads
+            .integer('start_city_id')
+            .unsigned()
+            .notNullable()
+            .references('id')
+            .inTable('cities')
+            .onDelete('CASCADE')
+            .onUpdate('CASCADE');
+
+        roads
+            .integer('end_city_id')
+            .unsigned()
+            .notNullable()
+            .references('id')
+            .inTable('cities')
+            .onDelete('CASCADE')
+            .onUpdate('CASCADE');
+
+        roads
+            .integer('distance')
+            .unsigned()
+            .notNullable()
+    });
+};
+
+exports.down = function(knex) {
+    return knex.schema.dropTableIfExists('roads');
+};