DROP TABLE - PURGE

Oracle Database 10g gives you the extra feature to drop your table and put them in the Recycle bin, This feature was introduced in 10g and it's not in earlier versions. Once you drop the table you can use Flashback query to retrieve that table from the Recycle bin.
If you want to remove the table permanently from the database also from Recycle bin then you have to use PURGE (just like shift+delete key in Windows).
And you cannot roll back Drop Table and Purge Clause.

Syntax given below.

Drop Table Table_name Purge;
It'll permanently remove and clears your storage space.

Drop Table Table_name
It will drop the table and send that table into the Recycle Bin.

Flashback Table Table_name to Before drop;
It will retrieve the Table from the Recycle Bin.

And also you can use this query to retrieve from Recycle Bin.

Select original_name, operation, droptime, from recyclebin;
Where Original_name is the table_name
Operation is drop that you did perform
Droptime, At what time you dropped the table.

To Clear the RecycleBin,
PURGE RECYCLEBIN;

Syed Sharique Imam: Different Types of Joins-

Syed Sharique Imam: Different Types of Joins-: "Joins A range of new join syntax are available that comply with the ANSI/ISO SQL: 1999 standards. CROSS JOIN The CROSS JOIN produces a ca..."

Different Types of Joins-

Joins

A range of new join syntax are available that comply with the ANSI/ISO SQL: 1999 standards.

CROSS JOIN

The CROSS JOIN produces a cartesian product.

ANSI/ISO Syntax

select e.ename, d.dname
from emp e cross join dept d;

Existing Syntax
select e.ename, d.dname
from emp e , dept d ;

NATURAL JOIN

The NATURAL JOIN performs a join for all columns with matching names in the two tables.

ANSI/ISO Syntax

select e.ename, d.dname
from emp e natural join dept d;

Existing Syntax

select e.ename, d.dname
from emp e , dept d
where e.deptno = d.deptno;

JOIN ... USING

The USING clause is used if several columns share the same name, but you do not wish to join using all of these common columns. The columns listed in the USING clause cannot have any qualifiers in the statement, including the WHERE clause.


ANSI/ISO Syntax

select e.ename, e.job, d.dname
from emp e join dept d
using (deptno)

Existing Syntax

select e.ename, e.job, d.dname
from emp e , dept d
where e.deptno = d.deptno

Multiple Joins

Multiple Joins are those where more than two tables are joined

ANSI/ISO Syntax

select first_name, last_name, department_name, city
from employees e join departments d on (e.department_id = d.department_id)
join locations l on (d.location_id = l.location_id)

Existing Syntax

select first_name, last_name, department_name, city
from employees e , departments d , locations l
where e.department_id = d.department_id
and d.location_id = l.location_id

OUTER JOIN

There are three variations on the outer join. The LEFT OUTER JOIN returns all the rows from the table on the left side of the join, along with the values from the right hand side, or NULLs if a matching row doesn't exist. The RIGHT OUTER JOIN does the reverse of this. Finally, the FULL OUTER JOIN returns all rows from both tables, filling in any blanks with nulls.


ANSI/ISO Syntax

select l.city, d.department_name
from locations l
left outer join
departments d
on (l.location_id = d.location_id)


Existing Syntax

select l.city, d.department_name
from locations l , departments d
where l.location_id = d.location_id(+)


ANSI/ISO Syntax

select l.city, d.department_name
from locations l
right outer join
departments d
on (l.location_id = d.location_id)


Existing Syntax

select l.city, d.department_name
from locations l , departments d
where l.location_id(+) = d.location_id


ANSI/ISO Syntax

select l.city, d.department_name
from locations l
full outer join
departments d
on (l.location_id = d.location_id)


Existing Syntax

No Equivalent!