create table customer
(cust_id integer not null,
cust_name char(20) not null ,
cust_address varchar2(200) ,
emp_id integer not null,
constraint pk_customer primary key(cust_id)
);
create table account
(account_number integer not null,
account_balance number(8,2) not null,
constraint pk_acount primary key(account_number)
);
create table has
(cust_id integer not null,
account_number integer not null,
constraint pk_has primary key(cust_id, account_number)
);
alter table has
add constraint fk_account_has foreign key(account_number)
references account(account_number);
alter table has
add constraint fk_customer_has foreign key(cust_id)
references customer(cust_id);
alter table customer
add constraint fk_employee_customer foreign key(emp_id)
references employee(emp_id);
Q1 Show all the information about the customers with account number 101 and account number 102
Q2 Show the account numbers and the customer IDs for all customers with account balance higher than 500.
Q3 Show all the information about the customers with account balances that differ from 500.
That would be something like this:
select c.cust_id, c.cust_address, c.cust_address
from customer c join has h on h.cust_id = c.cust_id
where h.account_number in (101, 102);
I suggest you STOP reading now and - looking at the first example - try to write the next 2 queries yourself.
select c.cust_id, h.account_Number
from customer c join has h on h.cust_id = c.cust_id
join account a on a.account_number = h.account_number
where a.account_balance > 500;
select c.cust_id, c.cust_address, c.cust_address
from customer c join has h on h.cust_id = c.cust_id
join account a on a.account_number = h.account_number
where a.account_balance <> 500;
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