索引：（customCate,creator)
1：
explain select * from tb where customCate in ('4028487718bc5d980118bd277fc40000','402848771a0449fc011a044afca60001','402848771a0449fc011a05672a260655','402848771a05fb0e011a0a50401b058f') and creator ='4028487718bc5d980118bd277fc40069';
+----+-------------+-------------+-------+------------------------------------------+------------------------+---------+------+-------+-------------+
 

| id | select_type | table       | type  | possible_keys                            | key                    | key_len | ref  | rows  | Extra       |
+----+-------------+-------------+-------+------------------------------------------+------------------------+---------+------+-------+-------------+
 

|  1 | SIMPLE      | tb          | range | idx_customCate_creator,idx_creator_releD | idx_customCate_creator | 198     | NULL | 16371 | Using where |
+----+-------------+-------------+-------+------------------------------------------+------------------------+---------+------+-------+-------------+
 


執行計劃裡的Type為range，但是in屬於多個等值條件，可以繼續用第2個索引，和>,<情況不一樣。

2：
explain select * from tb where customCate in  ('402848771a05fb0e011a0a50401b058f','402848771a05fb0e011a0a506eab0590','402848771a05fb0e011a0a50c90f0592') order by creator;
+----+-------------+-------------+-------+------------------------+------------------------+---------+------+-------+-----------------------------+
| id | select_type | table       | type  | possible_keys          | key                    | key_len | ref  | rows  | Extra                       |
+----+-------------+-------------+-------+------------------------+------------------------+---------+------+-------+-----------------------------+
|  1 | SIMPLE      | tb          | range | idx_customCate_creator | idx_customCate_creator | 99      | NULL | 19869 | Using where; Using filesort |
+----+-------------+-------------+-------+------------------------+------------------------+---------+------+-------+-----------------------------+

對於Order By、Group By 第2個索引不能用，和>,< 情況一樣。

3:
explain select * from tb 
where 
    customCate in ('402848771a05fb0e011a0a50401b058f','402848771a05fb0e011a0a506eab0590','402848771a05fb0e011a0a50c90f0592') 
and 
    creator in ('4028487718bc5d980118bd277fc40069','4028487718dbd37a0118e54b53e300e8','4028487718dbd37a0118e54b53e300e8');
+----+-------------+-------------+-------+------------------------------------------+------------------------+---------+------+-------+-------------+
| id | select_type | table       | type  | possible_keys                            | key                    | key_len | ref  | rows  | Extra       |
+----+-------------+-------------+-------+------------------------------------------+------------------------+---------+------+-------+-------------+
|  1 | SIMPLE      | tb          | range | idx_customCate_creator,idx_creator_releD | idx_customCate_creator | 198     | NULL | 19881 | Using where |
+----+-------------+-------------+-------+------------------------------------------+------------------------+---------+------+-------+-------------+
1 row in set (0.00 sec)

可以在多個欄位一起用多個等值條件查詢，多個欄位的索引都可以被利用，和>,<情況不一樣。

4:IN 用法不適用於 NOT IN 

explain select * from tb where customCate  not in ('4028487718bc5d980118bd277fc40000','402848771a05fb0e011a0a506eab0590','402848771a05fb0e011a0a50c90f0592') and creator ='4028487718bc5d980118bd277fc40069';
+----+-------------+-------------+------+------------------------------------------+-------------------+---------+-------+-------+-------------+
| id | select_type | table       | type | possible_keys                            | key               | key_len | ref   | rows  | Extra       |
+----+-------------+-------------+------+------------------------------------------+-------------------+---------+-------+-------+-------------+
|  1 | SIMPLE      | tb          | ref  | idx_customCate_creator,idx_creator_releD | idx_creator_releD | 99      | const | 42008 | Using where |
+----+-------------+-------------+------+------------------------------------------+-------------------+---------+-------+-------+-------------+