在子查询返回多行时总结值。 （我的用例是2行）

Question

我有多个行通过查询。我如何分组这些行来总结一些行的值并留下余下的行。

set total_fees1 = (select (f.total_Fees2) from fee_Collection f where f.student_Id =minstudent_Id); 
      set total_fees2 = (select (f.total_Fees3) from fee_Collection f where f.student_Id =minstudent_Id); 
      set paid_amount1 = (select (f.paid_amount2) from fee_Collection f where f.student_Id =minstudent_Id); 
      set paid_amount2 = (select (f.paid_amount3) from fee_Collection f where f.student_Id =minstudent_Id); 

对于某些情况，上述查询返回2行。现在，我必须在收到多于1行的情况下添加paid_amount值，并获取total_fees字段的第一行值。

Answer 1

这将是：

set total_fees1 = (select (f.total_Fees2) from fee_Collection f where f.student_Id =minstudent_Id LIMIT 1); 
     set total_fees2 = (select (f.total_Fees3) from fee_Collection f where f.student_Id =minstudent_Id LIMIT 1); 
     set paid_amount1 = (select SUM(f.paid_amount2) from fee_Collection f where f.student_Id =minstudent_Id); 
     set paid_amount2 = (select SUM(f.paid_amount3) from fee_Collection f where f.student_Id =minstudent_Id);