Combining a Date and a Time Column into One Timestamp Column

How can I create a timestamp column from a date and开发者_如何学编程 a time column in Oracle?

Oracle databases have a date data type (which contains date and time down the second) and several timestamp data types (which have date date and time with subsecond granularity - up to 9 digits).
There are two interval data types (year to month and day to second). There is no time data type.

And in addition to Chip's explanation, you can create a timestamp by using the TO_TIMESTAMP function

Regards,
Rob.