Please try the great god teach a lot of methods can't

CodePudding user response:

Use case select field values
The select case
The when t1. A & gt; T2) and a t1) a & gt; T3. Then a t1. A else
The when t2. A> T3. Then a t2. A else t3. A
End
.

The from t1, t2, t3, where t1. Id=t2. The id and t2. Id=t3. Id

Different database, grammar may be slightly different