对子查询返回多行时的值进行求和。(我的用例是2行)

Question

通过查询，我有多行数据。如何对这些行进行分组，以求出其中一些行的值，并留下其余行的值。

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);

上述查询在某些情况下会返回2行。现在，我必须在获得超过1行的情况下添加paid_amount值，并取total_fees字段的第一行的值。

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);