1. JOINS allow users to combine data from two or more tables based on related columns between them. There are different types of joins including inner, left outer, right outer, and full outer joins. 2. GROUP BY is used with aggregate functions to group query results by one or more columns. HAVING is used with GROUP BY to filter groups. 3. UNION combines the results of multiple select statements into a single result set by removing duplicate rows.

1. JOINS
BY: Hira Khalid

2. JOINS
It is used to combine
rows from two or
more tables, based
on a related column
between them.
SELECT * FROM order JOIN customer
ON order.depno=customer.depno;
QUERY

3. TYPES OF JOINS
(INNER)
JOIN
LEFT
(OUTER)
JOIN
RIGHT
(OUTER)
JOIN
FULL
(OUTER)
JOIN

4. INNER JOIN
The INNER JOIN keyword selects records
that have matching values in both tables.
SYNTAX
SELECT * FROM orders JOIN customer
ON orders.depno=customers.depno;

5. EXAMPLE:
OrderID CustomerID EmployeeID OrderDate ShipperID
10308 2 7 1996-09-18 3
10309 37 3 1996-09-19 1
10310 77 8 1996-09-20 2
CustomerI
D
Customer
Name
ContactNam
e
Address City PostalCod
e
Country
1 Alfreds
Futterkis
te
Maria
Anders
Obere Str.
57
Berli
n
12209 Germany
2 Ana
Trujillo
Empared
ados y
helados
Ana Trujillo Avda. de la
Constituci
ón 2222
Méxic
o D.F.
05021 Mexico
3 Antonio
Moreno
Antonio
Moreno
Mataderos
2312
Méxic
o D.F.
05023 Mexico
SELECT * FROM order
INNER JOIN customer ON
order.depno=customer.depno;

6. JOIN Three Tables:
SELECT Orders.OrderID, Customers.CustomerName,
Shippers.ShipperName
FROM ((Orders
INNER JOIN Customers ON Orders.CustomerID =
Customers.CustomerID)
INNER JOIN Shippers ON Orders.ShipperID =
Shippers.ShipperID);
EXAMPLE:

7. LEFT JOIN
• The LEFT JOIN keyword
returns all records from
the left table (table1), and
the matched records from
the right table (table2).
The result is NULL from
the right side, if there is
no match.
SYNTAX
•SELECT column_name(s)
FROM table1
LEFT JOIN table2 ON table1.
column_name = table2.colum
n_name;

8. EXAMPLE:
OrderID CustomerID EmployeeID OrderDate ShipperID
10308 2 7 1996-09-18 3
10309 37 3 1996-09-19 1
10310 77 8 1996-09-20 2
CustomerI
D
Custome
rName
ContactN
ame
Address City PostalCod
e
Country
1 Alfreds
Futterki
ste
Maria
Anders
Obere Str.
57
Berlin 12209 Germany
2 Ana
Trujillo
Empare
dados y
helados
Ana
Trujillo
Avda. de
la
Constituci
ón 2222
México
D.F.
05021 Mexico
3 Antonio
Moreno
Taquerí
a
Antonio
Moreno
Matadero
s 2312
México
D.F.
05023 Mexico
SELECT * FROM customer LEFT JOIN
order
ON customer.customerID=order.customerID;

9. RIGHT JOIN
The RIGHT JOIN keyword returns all records from the right table
(table2), and the matched records from the left table (table1). The
result is NULL from the left side, when there is no match.
SYNTAX
•SELECT column_name(s)
FROM table1
RIGHT JOIN table2 ON table1.column_name = table2.column_name

10. OrderI
D
CustomerI
D
EmployeeI
D
OrderDate ShipperID
10308 2 7 1996-09-18 3
10309 37 3 1996-09-19 1
10310 77 8 1996-09-20 2
EmployeeID LastName FirstName BirthDate Photo
1 Davolio Nancy 12/8/1968 EmpID1.pic
2 Fuller Andrew 2/19/1952 EmpID2.pic
3 Leverling Janet 8/30/1963 EmpID3.pic
EXAMPLE:
SELECT * FROM order RIGHT JOIN
employee
ON
order.EmployeeID=employee.EmployeeID;

11. FULL OUTER JOIN
Return all records when there is a match
in either left (table1) or right (table2) table
records.
SYNTAX
SELECT column_name(s)
FROM table1
FULL OUTER JOIN table2 ON table1.col
umn_name = table2.column_name;

12. EXAMPLE:
Customer
ID
Customer
Name
ContactN
ame
Address City PostalCod
e
Country
1 Alfreds
Futterkist
e
Maria
Anders
Obere Str.
57
Berlin 12209 Germany
2 Ana
Trujillo
Empareda
dos y
helados
Ana
Trujillo
Avda. de
la
Constituci
ón 2222
México
D.F.
05021 Mexico
3 Antonio
Moreno
Taquería
Antonio
Moreno
Matadero
s 2312
México
D.F.
05023 Mexico
OrderID CustomerID EmployeeID OrderDate ShipperID
10308 2 7 1996-09-18 3
10309 37 3 1996-09-19 1
10310 77 8 1996-09-20 2
SELECT Customers.CustomerName,
Orders.OrderID
FROM Customers
FULL OUTER JOIN Orders
ON Customers.CustomerID=Orders.CustomerI
D;

13. SELF JOIN
A self JOIN is
a regular join,
but the table
is joined with
itself.
SYNTAX
SELECT column_n
ame(s)
FROM table1 T1,
table1 T2
WHERE condition;

14. EXAMPLE:
SELECT a.EmpName Name,b.EmpName Name
FROM emp a
INNER JOIN emp b
ON a.ManagerID=b.EmpID
RESULT:

15. UNION Each SELECT
statement within
UNION must have
the same number of
columns
The columns must
also have similar
data types
The columns in
each SELECT
statement must
also be in the same
order
The operator is
used to combine
the result-set of
two or more
SELECT
statements.

16. QUERY:
To allow
duplicate
values, use
UNION
ALL:
The UNION
operator
selects only
distinct values
by default
SELECT column_n
ame(s) FROM table
1 UNION ALL
SELECT column_n
ame(s) FROM table
2;

17. EXAMPLE:
Custome
rID
Custome
rName
Contact
Name
Address City PostalCo
de
Country
1 Alfreds
Futterkis
te
Maria
Anders
Obere
Str. 57
Berlin 12209 Germany
2 Ana
Trujillo
Empared
ados y
helados
Ana
Trujillo
Avda. de
la
Constitu
ción 2222
México
D.F.
05021 Mexico
3 Antonio
Moreno
Taquería
Antonio
Moreno
Matader
os 2312
México
D.F.
05023 Mexico
SELECT country FROM custo
mer
UNION
SELECT country FROM shipp
er
ORDER BY country
RESULT:

18. GROUP BY
The statement is often used
with aggregate functions
(COUNT, MAX, MIN, SUM,
AVG) to group the result-set by
one or more columns.
SYNTAX:
SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
ORDER BY column_name(s);

19. EXAMPLE:
CustomerI
D
Customer
Name
ContactNa
me
Address City PostalCod
e
Country
1 Alfreds
Futterkist
e
Maria
Anders
Obere Str.
57
Berlin 12209 Germany
2 Ana
Trujillo
Empareda
dos y
helados
Ana
Trujillo
Avda. de la
Constituci
ón 2222
México
D.F.
05021 Mexico
3 Antonio
Moreno
Taquería
Antonio
Moreno
Mataderos
2312
México
D.F.
05023 Mexico
SELECT COUNT(Custo
merID), Country
FROM Customers
GROUP BY Country;
RESULT: SELECT COUNT(City)
FROM customer
GROUP BY City

20. HAVING
The HAVING clause was added to SQL because the
WHERE keyword could not be used with aggregate
functions.
SYNTAX:
SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
HAVING condition
ORDER BY column_name(s);

21. EXAMPLE:
SELECT
COUNT(CustomerID),Country
FROM customer
GROUP BY (CustomerID)
HAVING (CustomerID)<>3
Customer
ID
Customer
Name
ContactN
ame
Address City PostalCod
e
Country
1 Alfreds
Futterkist
e
Maria
Anders
Obere Str.
57
Berlin 12209 Germany
2 Ana
Trujillo
Empareda
dos y
helados
Ana
Trujillo
Avda. de
la
Constituci
ón 2222
México
D.F.
05021 Mexico
3 Antonio
Moreno
Taquería
Antonio
Moreno
Mataderos
2312
México
D.F.
05023 Mexico
RESULT: