- The grouping criteria of enum grouping can be from the expression. For example, group the employees into 3 teams by a certain criteria, a team for those younger than 30, a team for those aged between 30 and 40, and a team for those order than 40.
- Enum grouping is also a kind of non-equal group which is generally characterized with “result is obtained in a way consistent with the grouping criteria). You can directly and simply implement some features that are hard for SQL to implement.
- The unwanted group can be removed directly. For example, to group the data into 2 groups, one group for those between 30 and 40, and one group for those higher than 40, then the result is collected in only these 2 groups. (For SQL, there will be an extra empty group).
- Even if a certain group of data is empty, the result of enum grouping operation will still keep this group. In the below example, suppose if there is not any employee younger than 30, then this group still exist with a count of member equaling 0 (this group does not exist for SQL).
- The non-equal grouping enables users to control the group member more flexibly. For example, to group into a team for employees between 20 and 40, and a team for employees between 30 and 50, then those aged between 30 and 40 can appear in either team or both teams. (For SQL, it is only allowed to appear in either team).