Обсуждение: UPDATE across tables

On Wed, 2002-08-07 at 12:01, Jake Matchett wrote:
> I need to update the primary key field in two tables sharing this field,
> I can't update separately because I get an integrity violation message
> that tells me the field is still being referenced from the other table,
> fair enough but is there any way of doing a joined/linked/double update
> to the primary key of both tables simultaneously? Something like: UPDATE
> table1.fieldx, table2.fieldx SET fieldx='yyyyy' WHERE fieldx='zzzzz';


The foreign key reference must be deferrable. Like this:

  CREATE TABLE b (id CHAR(1) PRIMARY KEY REFERENCES a DEFERRABLE, ...);

For the update, do both in one transaction, with deferred constraints:
  SET CONSTRAINTS ALL DEFERRED;
  BEGIN;
  UPDATE table1 ...
  UPDATE table2...
  END;


--
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight, UK
http://www.lfix.co.uk/oliver
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