refactor: flyway修改

backend/src/main/resources/db/migration/V14__area_code.sql

+CREATE TABLE `area_mapping`  (
+  `id` bigint(20) NOT NULL COMMENT 'id',
+  `province_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '省名称',
+  `province_code` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '省代码',
+  `city_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '市名称',
+  `city_code` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '市代码',
+  `county_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '县名称',
+  `county_code` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '县代码',
+  PRIMARY KEY (`id`) USING BTREE
+) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci;