Informix supports 2 different styles for the update - your one would have to
be written :
UPDATE djp SET(col1, col2) = ((SELECT col1,col2 FROM some_other_table))
Notice the double brackets !
The first signifies a list of values - the second is the brackets around the
subquery...
(NB If you try to reference the same table in the Update - you'll get an
error....)
For single columns you could still write :
UPDATE djp SET col1 = (SELECT col2 FROM some_other_table)
Notice - one more set of brackets on the right as on the left....
> UPDATE djp SET(col1, col2) = (SELECT col2, col1 FROM djp)