cop_trunc_date formats

## Variables

const | SqlUtil::DT_DAY = "D"
| Format unit: day.
const | SqlUtil::DT_HOUR = "H"
| Format unit: hour.
const | SqlUtil::DT_MINUTE = "m"
| Format unit: minute.
const | SqlUtil::DT_MONTH = "M"
| Format unit: month.
const | SqlUtil::DT_SECOND = "S"
| Format unit: hour.
const | SqlUtil::DT_YEAR = "Y"
| Format unit: year.

## Detailed Description

These are formatting constant which can be used in cop_trunc_date() formatting argument.

Input date used in the table below: 20.4.2017 14:27:34

Constant | Meaning | Example
DT_YEAR | Truncate date up to year | 1.1.2017 00:00:00
DT_MONTH | Truncate date up to month | 1.4.2017 00:00:00
DT_DAY | Truncate date up to day | 20.4.2017 00:00:00
DT_HOUR | Truncate date up to hour | 20.4.2017 14:00:00
DT_MINUTE | Truncate date up to minute | 20.4.2017 14:27:00
DT_SECOND | Truncate date up to second | 20.4.2017 14:27:34

Note
  Oracle: using `DT_SECOND` for `DATE` type does not make sense as the `DATE` resolution is up to seconds out of the box. On the other side `TINESTAMP` is truncated up to seconds with this operator.