Orm 原则2 DQL：如何按鉴别器列（STI）分组

我有以下原则2 STI车辆实体，它有两个名为Car和Bike的子类，需要按车辆类型计算车辆表中的项目。（例如：表格摘要：3辆汽车，5辆自行车.）

因此，我尝试了以下DQL查询，但都不起作用：

SELECT v, TYPE(v) as vtype, count(v.id) as cnt FROM Vehicle v GROUP BY TYPE(v);
SELECT v, count(v.id) as cnt, TYPE(v) as vtype FROM Vehicle v GROUP BY vtype;
SELECT v, count(v.id) as cnt, TYPE(v) as vtype FROM Vehicle v GROUP BY TYPE(vtype);

查询异常：

[Syntax Error] line 0, col 10: Error: Expected known function, got 'TYPE'

另一项：

[Semantical Error] line 0, col 83 near 'TYPE()': Error: Cannot group by undefined identification or result variable

有什么想法吗？（条令版本为2.3）

[Semantical Error] line 0, col 83 near 'TYPE()': Error: Cannot group by undefined identification or result variable