MySQL moves from one table update field to another

  • 2020-11-18 06:30:58
  • OfStack

Let's start with a few simple examples

Solution 1:1


update student s, city c
  set s.city_name = c.name
 where s.city_code = c.code;

Solution 2: Multiple columns


update a, b 

set a.title=b.title, a.name=b.name
where a.id=b.id

Solution 3: Subquery


update student s set city_name = (select name from city where code = s.city_code);

Let's look at a couple more of the ones that did it

For example, update the table tk_zyt_scenery_order to t_advs_order.


UPDATE t_advs_order SET
 
 attribute1=(SELECT o.order_state FROM tk_zyt_scenery_order o WHERE o.order_id=`on`),
 
 attribute2=(SELECT o.order_state FROM tk_zyt_scenery_order o WHERE o.order_id=`on`)
 
 WHERE EXISTS (SELECT o.order_state FROM tk_zyt_scenery_order o WHERE o.order_id=`on`);

In this way, the efficiency is relatively low and the writing method is optimized:


UPDATE t_advs_order a INNER JOIN tk_zyt_scenery_order s ON s.order_id=a.`on` SET
 
 a.attribute1=s.order_id,
 
 a.attribute2=s.order_id;


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