Question

如何将外国关键表的总和作为主要表格中的一种价值列入一个选择说明?

表1

id(PK)   name    description
-----------------------------

 1       test1      desc1
 2       test2      desc2

表2

id(FK)    value
-----------------
 1         5
 1         6
 2         7
 2         8

The result for the SQL select statement should be like

id     name   desc    sum(value)
----------------------------------
 1     test1  desc1        11

Answer 1

select 
  t.*, 
  ( select 
      sum(tt.value) 
    from table2 tt 
    where tt.id = t.id) sum_value
from table1

HTH

Answer 2

最明显的方法是:

select p.id, p.name, p.description, sum(f.value)
from p join f on f.id = p.id
group by p.id, p.name, p.description

或者说,在加入之前,明确将儿童价值观分类(但不能确定,对于甲骨文以外的制度来说,这一辛子是正确的):

select p.id, p.name, p.description, fgroup.valuesum
from p join (select id,sum(value) valuesum from f group by id) fgroup
     on p.id = fgroup.id

Answer 3

如何

SELECT T1.ID, T1.name, T1.description, SUM(T2.Value)
FROM Table1 T1
JOIN Table2 T2 ON T1.id = T2.ID
GROUP BY T1.ID, T1.name, T1.description

如果这种询问给你造成麻烦的话,不妨审查basics of JOINs。