ruby on rails - Update using Active Record -

how update field using other fields in single query ?

sql:

"update table_name set field1=fields2 + 1 id=123" 

tried these things, didn't work

model.update(123, :field => "field2 + 1") model.update(123, :field => :field2 + 1) model.update(123, "field = field2 + 1") 

don't want in 2 query.

model.update_all("field = field2 + 1", {:id => 123}) 

the second argument conditions, on update should happen