包括按ID对子级进行排序:

Including sorting children by id:

ORDER BY COALESCE(parent, id), parent IS NOT NULL, id

SQL小提琴示例

说明:

• COALESCE(parent, id):首先按(有效分组)父母的ID排序.
• parent IS NOT NULL:将父行放在组的顶部
• id:最后对所有子级进行排序(父级相同，并且parent不为空)

• COALESCE(parent, id): First sort by (effectively grouping together) the parent's id.
• parent IS NOT NULL: Put the parent row on top of the group
• id: Finally sort all the children (same parent, and parent is not null)