Which three descriptions are correct about the effects of the TRUNCATE command on a table（）
- AThe corresponding indexes for the table are also truncated.
- BDelete triggers on the table are fired during the execution of the TRUNCATE command.
- CThe child table is truncated when the TRUNCATE command is applied on the parent table.
- DThe high-water mark （HWM） is set to point to the first usable data block in the table segment.
- ENo undo or very little undo data is generated during the execution of the TRUNCATE command