Skip to main content

PLSQL Programming part 4 - SQL joins

/**
Do the following exercises for learning SQL joins
Pre-requisites: You must have CREATE privilege and some space allocated for you
**/

create table temp1
(
cust_id number,
cust_name varchar2(100),
addr1 varchar2(40),
addr2 varchar2(40),
addr3 varchar2(40),
addr4 varchar2(40),
pincode varchar2(40),
constraint cust_pk primary key ( cust_id )
);
/

create table service_tbl
(
cust_id number,
service_no number,
start_date date,
end_date date,
plan_type varchar2(10),
foreign key (cust_id) references temp1(cust_id)
);
/

alter table temp1 rename to cust_table;

Select * from cust_table;

insert into cust_table
values(100,'CUSTOMER 1','ADDRESS CODE 1','ADDRESS CODE 2','ADDRESS CODE 3','ADDRESS CODE 4',11111);
insert into cust_table
values(200,'CUSTOMER 2','ADDRESS CODE 1','ADDRESS CODE 2','ADDRESS CODE 3','ADDRESS CODE 4',11111);
insert into cust_table
values(300,'CUSTOMER 3','ADDRESS CODE 1','ADDRESS CODE 2','ADDRESS CODE 3','ADDRESS CODE 4',11111);
insert Into cust_table
values(400,'CUSTOMER 4','ADDRESS CODE 1','ADDRESS CODE 2','ADDRESS CODE 3','ADDRESS CODE 4',11111);
insert into cust_table
values(500,'CUSTOMER 5','ADDRESS CODE 1','ADDRESS CODE 2','ADDRESS CODE 3','ADDRESS CODE 4',11111);
insert into cust_table
values(600,'CUSTOMER 6','ADDRESS CODE 1','ADDRESS CODE 2','ADDRESS CODE 3','ADDRESS CODE 4',11111);
insert into cust_table
values(700,'CUSTOMER 6','ADDRESS CODE 1','ADDRESS CODE 2','ADDRESS CODE 3','ADDRESS CODE 4',11111);

commit;

Select *
from service_tbl;

insert into service_tbl
values(100,1032427,sysdate,null,'Post Paid');
insert into service_tbl
values(100,1032428,sysdate,null,'Post Paid');
insert into service_tbl
values(100,1032429,sysdate,null,'Post Paid');
insert into service_tbl
values(100,1032430,sysdate,null,'Post Paid');
insert into service_tbl
values(100,1032431,sysdate,null,'PrePaid');
insert into service_tbl
values(100,1032432,sysdate,null,'PrePaid');
insert into service_tbl
values(100,1032433,sysdate,null,'Post Paid');
insert into service_tbl
values(200,2032427,sysdate,null,'Post Paid');
insert into service_tbl
values(200,2032427,sysdate,null,'Post Paid');
insert into service_tbl
values(200,2032427,sysdate,null,'Post Paid');
insert into service_tbl
values(200,2032427,sysdate,null,'Post Paid');
insert into service_tbl
values(300,3032427,sysdate,null,'PrePaid');
insert into service_tbl
values(300,3032427,sysdate,null,'PrePaid');
insert into service_tbl
values(300,3032427,sysdate,null,'PrePaid');
insert into service_tbl
values(300,3032427,sysdate,null,'PrePaid');
insert into service_tbl
values(400,4032427,sysdate,null,'Post Paid');
insert into service_tbl
values(500,5032427,sysdate,null,'Post Paid');
insert into service_tbl
values(600,6032427,sysdate,null,'Post Paid');
insert into service_tbl
values(600,6032427,sysdate,null,'Post Paid');
insert into service_tbl
values(600,6032427,sysdate,null,'Post Paid');

commit;

/***
CARTESIAN PRODUCT
***/

Select *
from cust_table,service_tbl;

--It returns 140 rows

select count(*) from cust_table; -- Returns 7
select count(*) from service_tbl; --Returns 20 rows


/***
SELF JOIN
***/

Select *
from cust_table A,CUST_TABLE B;

--It returns 49 rows -- 7x7 ROWS

/***
EQUI JOINS
***/

Select *
from cust_table,SERVICE_TBL
WHERE cust_table.CUST_ID = SERVICE_TBL.CUST_ID;

--It returns 20 rows
--Returns only the records those satisy the condition
--Driving table or the leading table is duplicated for the no of records fetched in the joining table


/***
OUTER JOIN - LEFT

***/
--Modern syntax
Select *
from cust_table,SERVICE_TBL
WHERE cust_table.CUST_ID = SERVICE_TBL.CUST_ID(+);

--Old syntax
Select *
from cust_table left outer join SERVICE_TBL
on cust_table.CUST_ID = SERVICE_TBL.CUST_ID;
--It returns 21 rows
--Returns the records those satisfy the condition in serivce_tbl and those dont in cust_table
--For the cust_id 700 in cust_table, there are no child records in service_tbl
--So , in left outer join, it finds no matching records and adds a null set

/***
OUTER JOIN - RIGHT
***/

--Modern syntax
Select *
from cust_table,SERVICE_TBL
WHERE cust_table.CUST_ID(+) = SERVICE_TBL.CUST_ID;

--Old syntax
Select *
from cust_table right outer join SERVICE_TBL
on cust_table.CUST_ID = SERVICE_TBL.CUST_ID;
--It returns 20 rows
--Returns the records those satisy the condition in cust_table and those dont in service_tbl

Comments

Rosewell said…
nice post!
keep writing
July 3, 2013 at 7:35 AM
Post a Comment

Popular posts from this blog

Design and Operations ( Employee- Model )

-- DB design drop table emp_Salary; drop table emp_Designation; drop table emp; drop table Designations; drop table Departments; drop table Salary_Bands; drop table Addresses; Create table emp( emp_id number, emp_Name varchar2(20), emp_address_id varchar2(10), emp_created_date date, emp_created_by varchar2(20), constraint e_pk primary key(emp_id) ); Create table Departments( dept_id number, dept_name Varchar2(20), constraints dept_pk primary key(dept_id) ); Create table Designations( dept_id number references Departments(dept_id), desg_id number, desg_description varchar2(20), constraints desg_pk primary key(dept_id,desg_id) ); Create table emp_Designation( emp_id number references emp(emp_id), emp_des_dept_id number references departments(dept_...
Post a Comment
Read more

How to remove duplicate rows without using DISTINCT or ROWID or GROUP BY methods in Oracle?

Make use of SET operators and CTAS (Create Table AS) method.. Example: Create table tmp_tb1 as Select * from table1 intersect Select * from table1; truncate table table1; insert into table1 select * from tmp_tb1; -- This will now have removed all duplicates in the table... commit; *** You can use UNION operator in place of INTERSECT
2 comments
Read more

Identify current and prev details of a customer

  create table customer_rating( id char, name char, irrating char, jcrrating char, procDate date, flag char ); insert into customer_rating values('A','D','X','Y','28-Jul-21','M'); insert into customer_rating values('A','D','M','L','27-Jul-21','M'); Select cr.id, cr.name, cr_prev.irrating pcob_rating, cr.irrating cob_rating, cr_prev.jcrrating pcob_jcr_rating, cr.jcrrating cob_jcr_rating From Customer_Rating cr join Customer_Rating cr_Prev  ON cr.procdate = '28-Jul-21' AND cr_prev.id = cr.id AND cr_prev.procdate = (  Select max(procdate) from Customer_Rating  Where id=cr.id and procdate < cr.procdate ) ;
Post a Comment
Read more