Updated the commit to match @NathanQingyangXu's suggestion.

Updated the commit to match @NathanQingyangXu's suggestion.

I still don't think you correctly understand the usage. It is sort of customized foreign key. In your testing case, I failed to see the point to use it. There is no customization necessity here. It is simply a common parent child relationship. If you studied the user guide link I provided above, you would gain a better understanding of its usage.

Updated the commit to match @NathanQingyangXu's suggestion.

I still don't think you correctly understand the usage. It is sort of customized foreign key. In your testing case, I failed to see the point to use it. There is no customization necessity here. It is simply a common parent child relationship. If you studied the user guide link I provided above, you would gain a better understanding of its usage.

This is a simplified case, but let's say I want to make a more complex JOIN than just a SELECT * FROM child; In those cases I would need the @JoinFormula.

Updated the commit to match @NathanQingyangXu's suggestion.

I still don't think you correctly understand the usage. It is sort of customized foreign key. In your testing case, I failed to see the point to use it. There is no customization necessity here. It is simply a common parent child relationship. If you studied the user guide link I provided above, you would gain a better understanding of its usage.

This is a simplified case, but let's say I want to make a more complex JOIN than just a SELECT * FROM child; In those cases I would need the @JoinFormula.

Yeah, but then there would not be testing failure any more.

Yeah, but then there would not be testing failure any more.

I don't get what are you saying. This faliure occurs whatever you put in the custom @JoinFormula. It doesn't matter if it is a simple SELECT or a complex one.