问题
I have three tables Branch, Account_table and customer. I am trying to write a SQL statement for:
At each branch find customers who have the highest balance in their savings account. Displaying their names, the balance, the branch ID and the free overdraft limit in their current accounts.
I have created three tables and insert data:
Branch Table
BID BADDRESS.STREET BADDRESS.CITY BADDRESS.P
---------- -------------------- -------------------- ----------
901 Nicholson Street Edinburgh EH11 5AB
906 East End Garden Glasgow G181QP
912 Fredrick Street London LA112AS
918 Zink Terrace Edinburgh EH149UU
Account_table
ACCNUM ACCTYPE BALANCE BID.BID INRATE LIMITOFFREEOD OPENDATE
------- --------------- ---------- ---------- ---------- ------------- --------
1001 current 820.5 901 .005 800 01-MAY-11
1010 saving 2155 906 .02 0 08-MAR-10
1002 current 2600 912 .005 1000 10-APR-13
1011 saving 4140 918 .02 0 24-OCT-13
Customer Table
CUSTID CADDRESS.STREET CADDRESS.CITY CADDRESS.POSTCODE CNAME.FIRSTNAME CNAME.SURNAME
---------- -------------------- ----------- -------------------- --------------- -----------
1002 Adam Street Edinburgh EH112LQ Jack Smith
1003 Adam Street Edinburgh EH112LQ Anna Smith
1004 New Tweed Edinburgh EH1158L Liam Bain
1005 Dundas Street Edinburgh EH119MN Usman Afaque
1006 St Andres Square Edinburgh EH12LNM Claire Mackintosh
Branch(bID, street, city, p_code, bPhone)
Account(accNum, accType, balance, bID, inRate, limitOfFreeOD, openDate)
Customer(custID, street, city, postCode, title, firstName, surName, custHomePhone,custMobile1, custMobile2, niNum)
Bold is primary key Italic is foreign key (In object relational we don't use Join if I am right).
This what I am trying to do but failed
select c.custid,
(select max(balance) from account_table a
where c.CUSTID = a.bid.bid
and a.acctype='saving' )as highest_saving,
c.cname.firstname,c.CNAME.surname
from customer c;
Any help? Thanks.
回答1:
You are missing custID column in account table. I have added a few more rows of data to create the test case for your requirement.
drop table acct;
drop table branch;
drop table customer;
create table branch(bid number primary key, addr_street varchar2(100), addr_city varchar2(100), addr_p varchar2(20));
insert into branch values(901,'Nicholson Street','Edinburgh','EH11 5AB');
insert into branch values(906,'East End Garden','Glasgow','G181QP');
insert into branch values(912,'Fredrick Street','London','LA112AS');
insert into branch values(918,'Zink Terrace','Edinburgh','EH149UU');
commit;
select * from branch;
Output:
BID ADDR_STREET ADDR_CITY ADDR_P
901 Nicholson Street Edinburgh EH11 5AB
906 East End Garden Glasgow G181QP
912 Fredrick Street London LA112AS
918 Zink Terrace Edinburgh EH149UU
create table customer(custid number primary key, caddr_street varchar2(100), caddr_city varchar2(100),
caddr_p varchar2(10), fname varchar2(100), lname varchar2(100));
insert into customer values(1002,'Adam Street','Edinburgh','EH112LQ','Jack','Smith');
insert into customer values(1003,'Adam Street','Edinburgh','EH112LQ','Anna','Smith');
insert into customer values(1004,'New Tweed','Edinburgh','EH1158L','Liam','Bain');
insert into customer values(1005,'Dundas Street','Edinburgh','EH119MN','Usman','Afaque');
insert into customer values(1006,'St Andres Square','Edinburgh','EH12LNM','Claire','Mackintosh');
commit;
select * from customer;
Output:
CUSTID CADDR_STREET CADDR_CITY CADDR_P FNAME LNAME
1002 Adam Street Edinburgh EH112LQ Jack Smith
1003 Adam Street Edinburgh EH112LQ Anna Smith
1004 New Tweed Edinburgh EH1158L Liam Bain
1005 Dundas Street Edinburgh EH119MN Usman Afaque
1006 St Andres Square Edinburgh EH12LNM Claire Mackintosh
create table acct(accnum number primary key, acctype varchar2(20), balance number, bid number
constraint acct_fk1 references branch(bid),
inrate number, LIMITOFFREEOD number, OPENDATE date, custid number
constraint acct_fk2 references customer(custid));
insert into acct values(1001,'current',820.5,901,0.005,800,to_date('01-MAY-11','dd-mon-yy'),1002);
insert into acct values(1010,'saving',2155,906,0.02,0,to_date('08-MAR-10','dd-mon-yy'),1002);
insert into acct values(1002,'current',2600,912,0.005,1000,to_date('10-APR-13','dd-mon-yy'),1006);
insert into acct values(1011,'saving',4140,918,0.02,0,to_date('24-OCT-13','dd-mon-yy'),1004);
insert into acct values(1012,'saving',4155,906,0.02,0,to_date('08-MAR-10','dd-mon-yy'),1004);
insert into acct values(1013,'current',2600,918,0.005,1000,to_date('10-APR-13','dd-mon-yy'),1004);
commit;
select * from acct;
Output:
ACCNUM ACCTYPE BALANCE BID INRATE LIMITOFFREEOD OPENDATE CUSTID
1001 current 820.5 901 .005 800 01-MAY-11 1002
1010 saving 2155 906 .02 0 08-MAR-10 1002
1002 current 2600 912 .005 1000 10-APR-13 1006
1011 saving 4140 918 .02 0 24-OCT-13 1004
1012 saving 4155 906 .02 0 08-MAR-10 1004
1013 current 2600 918 .005 1000 10-APR-13 1004
select y.fname, y.lname, y.balance, y.bid,ac.accnum,ac.acctype,ac.LIMITOFFREEOD
from (select *
from (select b.bid, c.custid, a.accnum,a.balance,
row_number() over(partition by b.bid order by a.balance desc) rn,
c.fname, c.lname
from acct a
inner join
branch b
on a.bid = b.bid
inner join
customer c
on a.custid = c.custid
where a.acctype = 'saving') x
where x.rn = 1) y
left join
acct ac
on y.custid = ac.custid
and y.bid = ac.bid
and ac.acctype = 'current';
Output:
FNAME LNAME BALANCE BID ACCNUM ACCTYPE LIMITOFFREEOD
Liam Bain 4140 918 1013 current 1000
Liam Bain 4155 906 NULL NULL NULL
来源：https://stackoverflow.com/questions/49266565/how-to-extract-data-from-three-tables-using-sql-object-relational-statement-in-o