Can I use one class as Entity and ViewEntity - nestjs

Question

I'm working with Typeorm using MySQL database. I have a class as Entity and another class as ViewEntity. The question is why I need two separate Classes when they serve the same goal. Could I use the same Class with Entity and ViewEntity decorators?
Example Entity of Person class:
#Entity()
export class Person {
#PrimaryGeneratedColumn({ type: 'int', unsigned: true })
id: number;
#Column({length:50})
name: string;
#Column({type:'date'})
birthDate: string;
}
Another class for ViewEntity with the same properties added age property:
ViewEntity({
expression: `SELECT id, name, birthDate,
TIMESTAMPDIFF(YEAR,birthDate,CURDATE()) AS age FROM person;`
})
export class PersonView {
#ViewColumn()
id: number;
#ViewColumn()
name: string;
#ViewColumn()
birthDate: string;
#ViewColumn()
age: number;
}
To reduce redundant why I can't combine these two classes by doing this:
#Entity()
#ViewEntity({
name: 'PersonView',
expression: `SELECT id, name, birthDate,
TIMESTAMPDIFF(YEAR,birthDate,CURDATE()) AS age FROM person;`
})
export class Person{
#ViewColumn()
#PrimaryGeneratedColumn({ type: 'int', unsigned: true })
id: number;
#ViewColumn()
#Column({length:50})
name: string;
#ViewColumn()
#Column({type:'date'})
birthDate: string;
#ViewColumn()
age: number;
}
I searched in Typeorm documentation but they use a class only for ViewEntity. When I tried to test that I face a problem:
DataTypeNotSupportedError: Data type "" in "Person.age" is not supported by "mysql" database.
Also, how would I retrieve data? By doing dataSource.getRepository(Person) Person class has Entity and ViewEntity decorator then which type of entity will be retrieved? How would Typeorm distinguish between these two entities?