With PostgreSQL (I'm using the version 9.1) is it possible to do mass update with a single query a column value with the value of another column, but if the other column value is null, to use the value of a third column, and if the third one is absent to use the current datetime (all the column have type
I need to change
columnA columnB columnC null foo bar null null baz null null null
columnA columnB columnC foo foo bar baz null baz quz null null
quz is the current datetime.