how to update swap values of two rows with single

问题:

Is there a query with which i can exchange the values of two rows with single query?

回答1:

you can see the solution in this article

http://www.microshell.com/database/sql/swap-values-in-2-rows-sql/

look at the : The elegant way , make a join to get the data from the 2 rows to be swapped in 1 row, after that make an update is easy.

example :

UPDATE
rules AS rule1
JOIN rules AS rule2 ON
( rule1.rule_id = 1 AND rule2.rule_id = 4 )
SET
rule1.priority = rule2.priority,
rule2.priority = rule1.priority
;

回答2:

UPDATE my_table SET a=@tmp:=a, a=b, b=@tmp;