| a.user_id | a.school_id |
|---|---|
| 1233 | 22013 |
| 2346 | 22017 |
| 2344 | 23445 |
| 2247 | 22017 |
| ... | ... |
| b.user_id | b.term |
|---|---|
| 2346 | 1 |
| 2346 | 1 |
| 2346 | 2 |
| 2347 | 2 |
| 1233 | 1 |
| ... | ... |
如上两张表，根据a.school_id=22017得到它的user_id然后根据此user_id得到 b.term，并把term=1的变为term=2，把term=2的变为term=1
UPDATE b LEFT JOIN a ON a.user_id = b.user_id SET b.term = IF(b.term!=1,1,2) WHERE a.school_id = '22017'