极客观点
项目管理
HarmonyOS
表结构
CREATE TABLE `tmp_rt57517_20230407` (
`video_id` int(10) unsigned NOT NULL,
`key_id` varchar(64) NOT NULL COMMENT 'key id from tracking website',
`trackingWebsite_id` smallint(5) unsigned NOT NULL COMMENT 'tracking website id',
`is_svddb` enum('true','false') NOT NULL DEFAULT 'true' COMMENT 'filter meta by release date',
`is_svddb_match` enum('true','false') NOT NULL DEFAULT 'true' COMMENT 'filter meta by release date',
`match_count` int(11) DEFAULT NULL COMMENT '匹配到几个母本',
PRIMARY KEY (`video_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1查询：
test> select * from tmp_rt57517_20230407 limit 20;
+----------+------------------------------------------+--------------------+----------+----------------+-------------+
| video_id | key_id | trackingWebsite_id | is_svddb | is_svddb_match | match_count |
+----------+------------------------------------------+--------------------+----------+----------------+-------------+
| 692322 | ac10624689 | 62387 | false | false | <null> |
| 840950 | ac22481663 | 62387 | false | false | <null> |
| 840967 | ac22480945 | 62387 | false | false | <null> |
| 840970 | ac22480886 | 62387 | false | false | <null> |
| 954778 | ac22309422 | 62387 | false | false | <null> |
| 3089164 | ac4892812 | 62387 | false | false | <null> |
| 5057932 | ac20108789 | 62387 | false | false | <null> |
| 5058053 | ac19993753 | 62387 | false | false | <null> |
| 5345601 | ac27443729 | 62387 | false | false | <null> |
| 6321042 | 3xa3rdn7fitybn6 | 65134 | false | false | <null> |
| 8286417 | ac15802695 | 62387 | false | false | <null> |
| 8565348 | cbe03e2e27fa8ae02fa7610b2997875f | 346 | false | false | <null> |
| 11902698 | dXMvMzQ5MzExOTUyLzI1NzE5MzI5MS5zaHRtbA== | 50 | false | false | <null> |
| 13356859 | b0979xfjxvk | 65088 | false | false | <null> |
| 13357600 | n3061x4uv47 | 65088 | false | false | <null> |
| 14533625 | p093947flub | 65088 | false | false | <null> |
| 14727323 | t09318q679z | 65088 | false | false | <null> |
| 15017212 | h3102ndylt8 | 65088 | false | false | <null> |
| 15370451 | p0965hj95gh | 65088 | false | false | <null> |
| 16204303 | m30655a0d4n | 65088 | false | false | <null> |
+----------+------------------------------------------+--------------------+----------+----------------+-------------+
20 rows in set
Time: 0.008s
明明有 is_svddb_match = false，但是 count 就是 0？为什么？
test> select count(*) from tmp_rt57517_20230407 where is_svddb_match = false;
+----------+
| count(*) |
+----------+
| 0 |
+----------+
1 row in set
Time: 0.008s
test>test> select is_svddb_match, count(*) from tmp_rt57517_20230407 group by is_svddb_match;
+----------------+----------+
| is_svddb_match | count(*) |
+----------------+----------+
| false | 5960 |
| true | 45 |
+----------------+----------+where is_svddb_match = 0 有结果
test> select * from tmp_rt57517_20230407 where is_svddb_match = 1 limit 20;
+-----------+---------------------+--------------------+----------+----------------+-------------+
| video_id | key_id | trackingWebsite_id | is_svddb | is_svddb_match | match_count |
+-----------+---------------------+--------------------+----------+----------------+-------------+
| 275779907 | 6475104023140631053 | 64332 | true | true | 0 |
| 279461052 | 3xhwpd2epwqyu3e | 65134 | true | true | 0 |
| 283964496 | 3xbr4a2rprht5uw | 65134 | true | true | 0 |
| 284175991 | 3xss767ixb2qjyg | 65134 | true | true | 0 |
| 289997791 | 3xjes3ti73fnbjs | 65134 | true | true | 0 |
| 301838221 | 3xqpypnqitchjgm | 65134 | true | true | 0 |
| 301932463 | 3x25ge25c9g3rpg | 65134 | true | true | 0 |
| 301990424 | 3xu7npkhsbxzhsc | 65134 | true | true | 0 |
| 303408488 | 3xjcx3qky3ujhqe | 65134 | true | true | 1 |
| 304595913 | 3xnbkigvdbpz2na | 65134 | true | true | 0 |
| 343205878 | 3xxbbzv84fcah6g | 65134 | true | true | 0 |
| 366995789 | 3xf6ez29jppdqwe | 65134 | true | true | 0 |
| 367138943 | 3xcuvkt76n7wa6q | 65134 | true | true | 0 |
| 367140093 | 3xm7tdrr4r9bfc6 | 65134 | true | true | 0 |
| 367140153 | 3x28psqt5gds3dy | 65134 | true | true | 0 |
| 367547800 | 3xcxbic44gba46i | 65134 | true | true | 0 |
| 368914522 | 3xstmp9928279e4 | 65134 | true | true | 0 |
| 369027752 | 3x32qs6r2y96iyu | 65134 | true | true | 0 |
| 369069949 | 3xy6yrdmuijgp84 | 65134 | true | true | 0 |
| 369137177 | 3xucabuesbg6d8a | 65134 | true | true | 0 |
+-----------+---------------------+--------------------+----------+----------------+-------------+但是 where is_svddb_match = 0 没有结果
test> select * from tmp_rt57517_20230407 where is_svddb_match = 0 limit 20;
+----------+--------+--------------------+----------+----------------+-------------+
| video_id | key_id | trackingWebsite_id | is_svddb | is_svddb_match | match_count |
+----------+--------+--------------------+----------+----------------+-------------+
+----------+--------+--------------------+----------+----------------+-------------+
0 rows in set
Time: 0.008s为什么？
mysql
enum 的 index 是从 1 开始的。在上面的定义中，
'true'是1，'false'是2。所以判断=0是没有的，但是=1是有值的。true / false 在 mysql 里就是
1跟0。在 enum 值长得比较像整数的时候，会引起很多比较混乱的情况，参见Index Values for Enumeration Literals。直接写
= false，会被认为是= 0。需要= 'false'才能匹配 enum 串。