SQL - 我有一个“人”表和一个“帐户”表。如何按行列出所有人员，并为每个帐户类型设置一个余额列？

Question

我很难弄清楚如何为这个问题命名，所以我提前道歉。

这是我的情况：

我有一张桌子，里面只有人。我有另一个包含所有帐户的表，其中包含 personID、accountType 和 balance 列。一个人可以有多个帐户，有不同的帐户类型，并不是每个人都拥有所有不同的帐户类型。

如何编写一个查询，每行列出一个人，并为每个“帐户类型”的余额提供一列？

理想情况下，我的查询应该是这样的：

PersonID | Account Type 1 Bal | Account Type 2 Bal | Account Type 3 Bal |
-------------------------------------------------------------------------
    1    |         $100       |         null       |         null       |
    2    |         null       |         $12        |         $1300      |
    3    |         null       |         null       |         $5         |
    4    |         $150       |         null       |         null       |
    5    |         $65        |         $300       |         $45        |

我假设我会使用某种 case 语句，但我还没有弄明白。另外，如果他们有多个相同的帐户类型，我想我会正确使用 sum() 吗？

谢谢。

Answer 1

这样的东西应该适用于postgres

select p.person_id,
  (select sum(a.balance) from account a where a.person_id = p.person_id and a.account_type = 'Type1') type1_balance,
  (select sum(a.balance) from account a where a.person_id = p.person_id and a.account_type = 'Type2') type2_balance,
  (select sum(a.balance) from account a where a.person_id = p.person_id and a.account_type = 'Type3') type3_balance
from person p

sqlfiddle example

Answer 2

检查这是否有帮助 -

http://sqlfiddle.com/#!4/30ebb/10/0

CREATE TABLE person
    ("person_id" int, "name" varchar2(9))
;

INSERT ALL 
    INTO person ("person_id", "name")
         VALUES (1, '''Abcd''')
    INTO person ("person_id", "name")
         VALUES (2, '''xyz''')
    INTO person ("person_id", "name")
         VALUES (3, '''jjjjj''')
    INTO person ("person_id", "name")
         VALUES (4, '''sfds''')
    INTO person ("person_id", "name")
         VALUES (5, '''temp''')
SELECT * FROM dual
;

CREATE TABLE accounts
    ("personID" int, "accountType" int, "balance" int)
;

INSERT ALL 
    INTO accounts ("personID", "accountType", "balance")
         VALUES (1, 1, 100)
    INTO accounts ("personID", "accountType", "balance")
         VALUES (1, 2, 150)
    INTO accounts ("personID", "accountType", "balance")
         VALUES (2, 1, 20)
    INTO accounts ("personID", "accountType", "balance")
         VALUES (3, 1, 40)
    INTO accounts ("personID", "accountType", "balance")
         VALUES (3, 2, 440)
    INTO accounts ("personID", "accountType", "balance")
         VALUES (4, 1, 600)
    INTO accounts ("personID", "accountType", "balance")
         VALUES (5, 1, 43)
    INTO accounts ("personID", "accountType", "balance")
         VALUES (5, 2, 50)
SELECT * FROM dual
;

查询 -

select * from (
select p."person_id", a."accountType", a."balance"
from person p, accounts a
where p."person_id" = a."personID"
)
pivot (sum("balance") for "accountType" in (1 as acc_type1_bal,2 as acc_type2_bal));


person_id   ACC_TYPE1_BAL   ACC_TYPE2_BAL
1   100 150
2   20  (null)
4   600 (null)
5   43  50
3   40  440

Answer 3

select personid
      ,sum(ac1bal) accounttype1bal
      ,sum(ac2bal) accounttype2bal
      ,sum(ac3bal) accounttype3bal
from (
select persontable.personid
        ,case when (accounttype=1) then bal end ac1bal
        ,case when (accounttype=2) then bal end ac2bal
        ,case when (accounttype=3) then bal end ac3bal
from persontable
left join accounttable on persontable.personid = accounttable.personid
    )
group by personid