MySQL uses the method of updating linked tables with update

One 、 Preface

Before that java In the code , branch 2 step ：

1. Use select Query a result set
2. According to this result set , Use update Method to update the database

Two 、sql

Now you need not to change the code , use sql To achieve this step , A sample of ：

update a cs inner join 

(

SELECT cs.class_id,cs.user_id FROM a cs,b ss
WHERE cs.class_id = ss.classid AND cs.user_id = ss.user_id
AND cs.isDel IS NULL
AND ss.num >=10

) rrr on cs.user_id=rrr.user_id and cs.class_id=rrr.class_id 

set cs.type = '1';

explain ：

1.sql There is a piece in it , First, query a qualified result set
2. And then update a surface , Use the data in the qualified result set , Put the right a Exterior and interior type Change to 1.

3、 ... and 、 remarks

There's another way , You can put the qualified a Tabular id Find out , And then update a Tabular type when , according to id to update , Use multiple update Statement or use in Any sentence will do .