New SQL Commands in
Oracle
INNER JOINs
NATURAL JOIN
• Perform JOIN based on like columns in two tables.
The Like columns must be of the same name and
data type.
• ON clause is not required
• Natural Join
SELECT *
FROM
Cust NATURAL JOIN Emp;
USING
• Perform JOIN based on specified columns in two tables.
• The specified columns must have the same name and data
type.
• With “Using”
SELECT
*
FROM Cust JOIN Emp USING (city, age);
// This join is also called COLUMN name join in that it uses
// only column names specified in USING clause
• Without “Using”
SELECT *
FROM
Cust, Emp
WHERE Cust.city = Emp.City AND Cust.age=
Emp.Age;
ON
• Perform JOIN based on specified columns in two tables.
• Can be used for columns having different names
• With “ON”
SELECT *
FROM Cust JOIN Emp ON
Cust.cust_city=Emp.emp_city;
// This join is called CONDITION JOIN
SELECT *
FROM
Cust JOIN Emp
ON
(Cust.city = Emp.city AND Cust.age >
Emp.age);
Without “ON”
SELECT *
FROM
Cust, Emp
WHERE Cust.cust_city=Emp.emp_city;
SELECT *
FROM
Cust, Emp
WHERE (Cust.city = Emp.city AND
Cust.age > Emp.age);
CROSS JOIN
• Produces cross product of two tables, resulting in a
Cartesian join
• // With CROSS JOIN (On and Using clauses are
not allowed)
SELECT *
FROM
Cust CROSS JOIN Emp;
// Without CROSS JOIN
SELECT *
FROM
Cust, Emp;
OUTER JOIN
All the above joins are called INNER JOINs.
(a)
LEFT OUTER JOIN (all tuples in the left table are kept)
SELECT
*
FROMCust LEFT OUTER JOIN Emp Using (city);
SELECT
*
FROMCust LEFT OUTER JOIN Emp
ON
(Cust.city = Emp.City);
(b)
RIGHT OUTER JOIN (all tuples in right table are kept)
SELECT
*
FROMCust RIGHT OUTER JOIN Emp Using (city);
(c)
FULL OUTER JOIN
SELECT
*
FROMCust FULL OUTER JOIN Emp Using (city);
CASE Statement
Simple CASE Statements
SELECT
Fname, Lname,
(CASE
DNO
WHEN 1
THEN ‘Headquarters’
WHEN 4
THEN ‘Administration’
WHEN 5
THEN ‘Research’
ELSE
‘No department’
END) AS Department
FROM Employee;
Fname,Lname
John
Franklin
Alica
Department
Smith
Research
Wong
Research
Zelaya Administration
Searched CASE Statements
SELECT
Fname, Lname, Salary
(CASE
Salary
WHEN
Salary <= 25000
THEN 1500
WHEN Salary > 25000 AND Salary < 50000
THEN 1000
WHEN Salary > 50000 AND Salary < 100000 THEN 500
ELSE
0
END) “Bonus”
FROM Employee;
Fname, Lname
John Smith
FranklinWong
Alica Zelaya
Salary
30000
40000
25000
Bonus
1000
1000
1500