Question: [Apparently](http://wiki.postgresql.org/wiki/Working_with_Dates_and_Times_in_PostgreSQL), PostgreSQL doesn't have `DATEADD`, because you can just use the `+` or `-` operators.

I need to add a number of hours to a date, which is accomplished like this:

```
date_field + interval '8.25 hour' 

```

Which is great, but I need the number of hours to come from a field in the table. Would be something like this:

```
date_field + interval start_time 'hour' 

```

I can't find anywhere how to do this. Is this actually impossible?

I don't mind resorting to ugly hacks like taking the field value and dividing by 3600, multiplying by 86400. Whatever I need to do, but I haven't found any way to do that either.

Answer: 
Found the answer, [in another SO question](https://stackoverflow.com/questions/10909902/how-to-add-number-of-days-in-postgresql-datetime):

```
date + interval '1' minute * FLOOR(start_time * 60)

```

Hope that helps anyone
If anyone wants to add in time stamp then

```
select time '05:00' - interval '2 hours'    

```