MySQL ON DUPLICATE KEY UPDATE while inserting a result set from a query

问题

I am querying from tableONE and trying to insert the result set into tableTWO. This can cause a duplicate key error in tableTWO at times. So i want to ON DUPLICATE KEY UPDATE with the NEW determined value from the tableONE result set instead of ignoring it with ON DUPLICATE KEY UPDATE columnA = columnA.

INSERT INTO `simple_crimecount` (`date` , `city` , `crimecount`)(
    SELECT 
        `date`, 
        `city`,
        count(`crime_id`) AS `determined_crimecount`
    FROM `big_log_of_crimes`
    GROUP BY `date`, `city`
) ON DUPLICATE KEY UPDATE `crimecount` = `determined_crimecount`;
# instead of [ON DUPLICATE KEY UPDATE `crimecount` = `crimecount`];

It returns an error saying the following

Unknown column 'determined_crimecount' in 'field list'

回答1:

The problem is that in the duplicate key clauses you cannot use any grouping functions (such as COUNT. However, there is an easy way around this problem. You just assign the result of the COUNT(crime_id) call to a variable, which you can use in the duplicate key clauses. Your insert statement would then look like this:

INSERT INTO `simple_crimecount` (`date` , `city` , `crimecount`)(
    SELECT 
        `date`, 
        `city`,
        @determined_crimecount := count(`crime_id`) AS `determined_crimecount`
    FROM `big_log_of_crimes`
    GROUP BY `date`, `city`
) ON DUPLICATE KEY UPDATE `crimecount` = @determined_crimecount;

I have create an SQL Fiddle that shows you how it works: SQL-Fiddle

You could also use UPDATE crimecount = VALUES(crimecount) and no variables:

INSERT INTO `simple_crimecount` (`date` , `city` , `crimecount`)(
    SELECT 
        `date`, 
        `city`,
        count(`crime_id`) AS `determined_crimecount`
    FROM `big_log_of_crimes`
    GROUP BY `date`, `city`
) ON DUPLICATE KEY UPDATE `crimecount` = VALUES(crimecount);

See the SQL-Fiddle-2

来源：https://stackoverflow.com/questions/16935896/mysql-on-duplicate-key-update-while-inserting-a-result-set-from-a-query

标签

mysql

resultset

insert-update

duplicates