I need to convert couple of columns in one table in PSQL and I really dont want to drop the table to fix this (thats my last resort). Is there a way to do this, because when I write:

```
    ALTER TABLE table ALTER TABLE column type TIMESTAMP without time zone using column::TIMESTAMP without time zone; 

```

it doesnt work, says:

```
    ERROR:cannot cast type time without time zone to timestamp without time zone.

```

P.S. If its possible, I would like to avoid dropping columns because I already use indexes of those columns.