来自SELECT数组的一条语句中的UPDATE查询

Question

Hi I have 2 SQL statements

Statement 1:

SELECT id, name, version FROM mydb WHERE device IS NULL AND Activated=1 ORDER BY id ASC LIMIT 10

Statement 2:

UPDATE mydb SET device='$device' WHERE name IN ('$itemsArray')

I have been getting the $itemsArray array from the first statement, but now I need to combine these statements, and I am not sure how to go about it and still keep it efficient.

When I have tried it myself I get 0 rows affected:

UPDATE mydb SET device='$device' WHERE Name IN (SELECT name FROM mydb WHERE device IS NULL AND Activated=1 ORDER BY id ASC LIMIT 10)

Edit: Removed quotes from subquery. Now I get this error: "This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery'"

Using MySQL Version: 5.7.15

Answer 1

In the MySQL documentation for 5.7 it states "MySQL does not support LIMIT in subqueries for certain subquery operators"

http://dev.mysql.com/doc/refman/5.7/en/subquery-restrictions.html

I also found this related post here on subqueries error with the LIMIT keyword: MySQL - This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery

Hope this helps :)

Answer 2

Use JOIN to relate the subquery to the table.

UPDATE mydb AS t1
JOIN (SELECT name 
      FROM mydb 
      WHERE device IS NULL AND Activated=1 
      ORDER BY id ASC 
      LIMIT 10) AS t2 ON t1.Name = t2.Name
SET device = '$device'

Answer 3

This is the correct syntax looks more like this:

UPDATE mydb
    SET device = '$device'
    WHERE Name IN (SELECT name FROM mydb WHERE device IS NULL AND Activated=1 ORDER BY id ASC LIMIT 10);

A subquery should not be surrounded by quotes, like a string.

However, I don't think this will work for two reasons: (1) the table is the same and (2) the limit.

So, this might do what you want:

UPDATE mydb
    SET device = '$device'
    WHERE device IS NULL AND Activated = 1
    ORDER BY id ASC
    LIMIT 10;

You might need a more complicated query if you really want to update based on name and not id .

Answer 4

I suggest that you are working too hard. Get rid of the SELECT :

UPDATE mydb SET device='$device'
    WHERE device IS NULL AND Activated=1
    ORDER BY id ASC LIMIT 10;