UPDATE with INNER JOIN or MIN?

Question

I am trying to transfer some data between tables. The 'NEW' table can have multiple entries of the data that was originally not meant to have multiple entries in the 'OLD' table. I would like to take the data from the 'OLD' table and copy it over to the new table where the NEW.ID is the lowest where new.OtherID=old.OtherID, basically a MIN(ID) per group of OtherID's equal to each other.

'NEW' table

ID | OtherID | Data
1       1      NULL
2       1      NULL
3       2      NULL
4       3      NULL
5       3      NULL

'OLD'

OtherID | Data <br>
1            data1
2            data2
3            data3
4            data4
5            data5

Desired Outcome on updated 'NEW' table:

ID | OtherID | Data <br>
1       1       data1
2       1       NULL
3       2       data2
4       3       data3
5       3       NULL

etc

Thanks!

Answer 1

This is how you could use INNER JOIN with UPDATE in MySQL:

UPDATE NEW n
  INNER JOIN (
    SELECT
      OtherID,
      MIN(ID) AS ID
    FROM NEW
    GROUP BY OtherID
  ) m ON n.ID = m.ID
  INNER JOIN OLD o ON n.OtherID = o.OtherID
SET n.Data = o.Data

Answer 2

You can try:

UPDATE new
   SET Data = ( SELECT DATA FROM old WHERE otherID = new.otherID )
 WHERE NOT EXIST
       ( SELECT NULL FROM new AS new2
          WHERE new2.id < new.id
            AND new2.otherID = new.otherID )

Note that this is standard SQL92 and should work with any RDBMS.

Answer 3

This worked for me in PostgreSQL, though I may have gotten the quoting wrong for MySQL.

UPDATE newtable SET
 `Data` = oldtable.`Data`
FROM
 oldtable
WHERE
 newtable.`ID` IN (
  SELECT MIN(sub_newtable.`ID`)
  FROM newtable sub_newtable
  GROUP BY
   sub_newtable.`OtherID`
 )
 AND newtable.`OtherID` = oldtable.`OtherID`

Answer 4

You can use:

UPDATE `NEW` 
LEFT JOIN `OLD` 
    ON `NEW`.`OtherID` = `OLD`.`ID`
SET `NEW`.`Data` = `OLD`.`Data`

EDIT: I'm sorry, this will update all records that correspond to columns in OLD.