mysql inner jion查询的问题

在开发的时候使用MYSQL的inner join语句发现了一个很奇怪的问题，直接上表

建表

a表结构和数据如下

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for a
-- ----------------------------
DROP TABLE IF EXISTS `a`;
CREATE TABLE `a`  (
  `id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  `title` varchar(255) CHARACTER SET utf8 COLLATE utf8_unicode_ci NULL DEFAULT NULL,
  `sort_id` tinyint(1) NULL DEFAULT NULL,
  `created_at` datetime NULL DEFAULT NULL,
  `deleted_at` datetime NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_unicode_ci ROW_FORMAT = Dynamic;

SET FOREIGN_KEY_CHECKS = 1;

b表结构如下：

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for b
-- ----------------------------
DROP TABLE IF EXISTS `b`;
CREATE TABLE `b`  (
  `id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  `other_id` int(11) NOT NULL,
  `a_id` int(11) NOT NULL,
  `created_at` datetime NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8 COLLATE = utf8_unicode_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of b
-- ----------------------------

SET FOREIGN_KEY_CHECKS = 1;

插入数据

a表

INSERT INTO `test`.`a` (`id`, `title`, `sort_id`, `created_at`, `deleted_at`) VALUES (1, '标题1', 1, '2021-08-20 16:14:27', NULL);
INSERT INTO `test`.`a` (`id`, `title`, `sort_id`, `created_at`, `deleted_at`) VALUES (2, '标题1', 2, '2021-08-20 16:14:38', NULL);
INSERT INTO `test`.`a` (`id`, `title`, `sort_id`, `created_at`, `deleted_at`) VALUES (3, '标题1', 2, '2021-08-20 16:14:51', NULL);

b表

INSERT INTO `test`.`b` (`id`, `other_id`, `a_id`, `created_at`) VALUES (1, 9999, 9999, '2021-08-20 16:25:14');

使用inner join进行查询

查询1

select * from `a` inner join  `b` where `a`.`sort_id` = 2 and (`b`.`other_id` = 1 or `a`.`title` = "标题1") and `a`.`deleted_at` is null order by `a`.`created_at` desc limit 10 offset 0

能够正常查出结果，结果如下图

查询2

这次查询删除掉b表的所有数据，然后再执行上面的查询

-- 先执行
DELETE FROM b WHERE id=1;
--后执行
select * from `a` inner join  `b` where `a`.`sort_id` = 2 and (`b`.`other_id` = 1 or `a`.`title` = "标题1") and `a`.`deleted_at` is null order by `a`.`created_at` desc limit 10 offset 0;

结果为空，结果如下图

疑惑

不管是查询1还是查询2，a和b表不都是没有公共部分吗？为什么查询1能够查询出数据，而查询2却不行呢? 请大佬解惑，非常感谢