How to insert foreign key from pre-generated table? - sql

Question

I have 3 tables:
create table customer
(
customer_id integer primary key,
customer_first_name varchar2(50) not null,
customer_surrname varchar2(50) not null,
phone_number varchar2(15) not null,
customer_details varchar2(200) default 'There is no special notes'
);
create table place
(
table_number integer primary key,
table_details varchar2(200) default 'There is no details'
);
create table booking
(
booking_id integer primary key,
date_of_booking date,
number_of_persons number(2) not null,
customer_id integer not null,
foreign key(customer_id) references customer(customer_id),
table_number integer not null,
foreign key(table_number) references place(table_number)
);
I have to generate customer table using this kind of generator:
set SERVEROUTPUT on format wrapped;
set define off;
drop sequence customer_seq;
drop sequence place_seq;
--CUSTOMER TABLE INSERT ROW GENERATOR
create sequence customer_seq START WITH 1 INCREMENT BY 1 NOMAXVALUE;
CREATE OR REPLACE TRIGGER customer_id_trigger
BEFORE INSERT ON customer
FOR EACH ROW
BEGIN
SELECT customer_seq.nextval INTO :new.customer_id FROM dual;
END;
/
DELETE FROM customer;
DECLARE
TYPE TABSTR IS TABLE OF VARCHAR2(250);
first_name TABSTR;
surrname TABSTR;
qname number(5);
phonenum number(15);
details TABSTR;
BEGIN
first_name := TABSTR ('Jhon','Poul','Jesica','Arnold','Max','Teemo','Tim','Mikel','Michael',
'Kristian','Adela','Mari','Anastasia','Robert','Jim','Juana','Adward',
'Jana','Ola','Kristine','Natali','Corey','Chester','Naomi','Chin-Chou');
surrname := TABSTR ('Grey','Brown','Robins','Chiho','Lee','Das','Edwins','Porter','Potter',
'Dali','Jordan','Jordison','Fox','Washington','Bal','Pitney','Komarowski',
'Banks','Albra','Shwiger');
details := TABSTR ('Exellent Customer','Good Customer','Always drunked','Left big tips',
'Bad Customer','Did not pay last bill','New Customer','VIP client');
qname := 100; — CHANGE THIS TO MANAGE HOW MANY ROWS YOU WANT TO BE ADDED
FOR i IN 1..qname LOOP
phonenum := dbms_random.value(111111111,999999999);
INSERT INTO customer VALUES (NULL, first_name(dbms_random.value(1,25)),
surrname(dbms_random.value(1,20)), phonenum, details(dbms_random.value(1,8)));
END LOOP;
DBMS_OUTPUT.put_line('Customers done!');
END;
/
--TABLE INSERT
DELETE FROM place;
create sequence place_seq start with 1 increment by 1;
insert into place values (place_seq.nextval, 'Near the window');
insert into place values (place_seq.nextval, default);
insert into place values (place_seq.nextval, 'Near the door');
insert into place values (place_seq.nextval, 'Near the window');
insert into place values (place_seq.nextval, 'Near the window');
insert into place values (place_seq.nextval, default);
insert into place values (place_seq.nextval, 'Near the door');
insert into place values (place_seq.nextval, 'Big table');
insert into place values (place_seq.nextval, default);
insert into place values (place_seq.nextval, 'Big table');
So the question is how can I insert client_id in "booking" table which have one of the numbers in "customers" table? Because every time I regenerate data in "Customers" table numbers are changing so I should somehow select numbers in an array and then randomly choose one of them from this array. The thing is I don't really know how to select from table to array. Can anybody help?

Answer 1

For PL/SQL version you can use BULK COLLECT and standard sys.odcinumberlist array.
create sequence booking_seq start with 1 increment by 1;
declare
customerIds sys.odcinumberlist;
placeIds sys.odcinumberlist;
number_of_generated_records number := 150; -- number of records to be generated
begin
-- fill the array of customer_id values
select customer_id
bulk collect into customerIds
from customer;
-- fill the array of place numbers
select table_number
bulk collect into placeIds
from place;
for i in 1..number_of_generated_records loop
insert into booking(booking_id,date_of_booking,number_of_persons,customer_id,table_number)
values(
booking_seq.nextval, -- booking_id
trunc(sysdate) + round(dbms_random.value(1,365)), -- date_of_booking
round(dbms_random.value(1,99)), -- number_of_persons
customerIds(round(dbms_random.value(1,customerIds.count))), -- customer_id
placeIds(round(dbms_random.value(1,placeIds.count))) -- table_number
);
end loop;
end;
But, for your case I would prefer pure sql:
insert into booking(booking_id,date_of_booking,number_of_persons,customer_id,table_number)
with
customer_subq as (
select customer_id, row_number() over (order by customer_id) rn from customer
),
place_subq as (
select table_number, row_number() over (order by table_number) rn from place
),
params as (
select 1500 number_of_generated_records,
(select count(1) from customer) customer_count,
(select count(1) from place) place_count
from dual
),
random_numbers as (
select round(dbms_random.value(1,1000)) random_number1,
round(dbms_random.value(1,1000)) random_number2,
round(dbms_random.value(1,1000)) random_number3,
round(dbms_random.value(1,1000)) random_number4
from dual,params
connect by level <= number_of_generated_records
)
select booking_seq.nextval booking_id,
trunc(sysdate) + mod(random_number1,365) date_of_booking,
mod(random_number1,100) number_of_persons,
customer_id,
table_number
from random_numbers,
params,
customer_subq,
place_subq
where mod(random_number1,customer_count) + 1 = customer_subq.rn
and mod(random_number2,place_count) + 1 = place_subq.rn