Question

I have a CSV import into a temp_import_table in which I’m validating the imported data before commiting to the database (mysql 5.0.88).

I’m trying to search the records in the validation table for duplicate entries, but I can’t get it to work like this:

<cfquery datasource="#session.datasource#">
    UPDATE import_pricat_csv
    SET err = "ja", errtxt = "duplicate EAN"
    WHERE iln = <cfqueryparam value="#Session.logId#" cfsqltype="cf_sql_varchar" maxlength="16">
        AND ean IN (
            SELECT ean
            FROM import_pricat_csv
            GROUP BY ean
            HAVING COUNT(ean) > 1
            )
</cfquery>

This throws an error:

You can't specify target table 'import_pricat_csv' for update in FROM clause 

Question:
Is this not possible? Is there a better way than to loop once to get duplicates and a second time to set dup-records to err="yes"

Thanks!

Answer 1

You can use the multiple-table UPDATE syntax to join with the materialised group results:

UPDATE import_pricate_csv NATURAL JOIN (
  SELECT ean FROM import_pricate_csv GROUP BY ean HAVING COUNT(*) > 1
) t SET
  import_pricate_csv.err    = 'ja',
  import_pricate_csv.errtxt = 'duplicate EAN'
;