How to update from select with a Join

Question

How can I update a table that is also present in a subquery? Do I have to do it in 2 stages? (create a temporary table - put the selected data in it and then update the final table)

I am trying to update the invoiceLine table with the label of the network for each CTN.

The end result would be:

• invoiceLine

  ctn       network
  1234      network1
  2345      network2
  3456      network1
  

I have the following tables:

• invoiceLine

  ctn       network
  1234      null
  2345      null
  3456      null
  

• terminal

  ctn       network
  1234      1
  2345      2
  3456      1
  

• network

  id        label
  1         network1
  2         network2
  

I can run a select but I'm not sure how to update with a join:

update invoiceLine 
inner join terminal on terminal.ctn = invoiceLine.ctn 
set invoiceLine.network = 
(
  select network.label 
  from invoiceLine 
  inner join terminal on terminal.ctn = invoiceLine.ctn 
  inner join network on network.id = terminal.network
) 
where invoiceLine.ctn = terminal.ctn

but MySQL throws a

Error Code: 1093. You can't specify target table 'invoiceLine' for update in FROM clause

Solution 1

UPDATE invoiceLine
    INNER JOIN terminal
        ON invoiceLine.ctn = terminal.ctn
    INNER JOIN network
        ON terminal.network = network.id
    SET invoiceLine.network = network.label

Solution 2

UPDATE invoiceLine SET network = (
    SELECT label FROM network WHERE id = (
        SELECT network FROM terminal WHERE terminal.ctn = invoiceLine.ctn
    )
)

Comments

[Manse]

Works a treat ... thanks :-) - will accept your answer in 6 mins, when SO lets me !

[mlg]

And the WHERE and LIMIT keywords would go after the SET keyword.