SELECT without FROM clause

SELECT 'Test1' WHERE EXISTS (SELECT 1/0)

SELECT 'Test2' WHERE EXISTS (SELECT *)

Those 2 statements won't raise an Error in SQL SERVER!

Te results will be:

Test1

Test2

Of course that SELECT 1/0 or SELECT * will raise an Error.

In SQL SERVER the FROM clause is optional. 

This is why SELECT 1 , SELECT @P and SELECT @P=5 are permitted.

In other database systems (Like Oracle), SELECT statement without FROM clause is not permitted, and there is a dummy table "DUAL" with one row that is used to do such SELECT statements:

SELECT 1 FROM dual , SELECT @v FROM dual.

Another thing is that in EXISTS clause doesn't matter in terms of the syntax or result of the query.

Those 2 facts (SELECT without FROM is allowed and EXISTS doesn't matter in terms of the syntax) 

explains the behavior of the 2 statements above.

https://connect.microsoft.com/SQLServer/feedback/details/671475/select-test-where-exists-select#details

Paging in Oracle

select * 

from (select rownum,fld1,fld2,fld3... from bigtable where <<CONDITION>> ) 

where rownum between 1 to 100 -- or between 101 to 200, and so on....

http://www.codeproject.com/Tips/152837/Post-on-how-to-do-Paging-in-Oracle.aspx

Take answer even it NULL (Oracle)

where xxx = yyy (+)

Oracle DB export

exp full=y file=d1050338.dmp log=exp.log compress=n statistics=none consistent=y userid=system/pdsec@d1050338

exp full=n owner=super,pmx file=d1050338.dmp log=exp.log compress=n statistics=none consistent=y userid=system/pdsec@d1050338

Get NULLS first - Oracle

SELECT GENDER, TYPECAST, NAME FROM ACTOR

ORDER BY  TYPECAST NULLS FIRST

In Oracle, when sorting with "order by", NULL values are sorted last. By write "NULLS FIRST" - NULL will be sorted in the beginning.

Oracle alter table

http://www.techonthenet.com/sql/tables/alter_table.php

Primary Keys:

http://www.techonthenet.com/oracle/primary_keys.php

MSSQL and Oracle data-types Compared

http://download.oracle.com/docs/cd/E10405_01/doc/appdev.120/e10379/ss_oracle_compared.htm#i1026427