Database Testing: Database Testing basically include in the 
following areas
1.Data Validity Testing.
2.Data Integrity Testing.
3.Performance Related Testing
4.Testing of Procedure,Triggers and Functions

2> Defect life cycle
wht is defect:deviation from the requirment
bug:informal name given to defect
eror:mistake in programm
defect life cycle
open--assign-->fixed-->retest-fixed->close--ifnot->reopen

the defect life cycle is a part of test execution as a test 
engineer when i start executing the test cases i am found 
lot of bugs so i have to maintain certain proceegers
first we have to check in bug repository with all possible 
keywords
1.once i found bug then i send bug to development team and 
cc to test lead
2.they evaluate the bug whether the bug is assigned or not 
different kind of responses like
a.bug reject b.duplicate c.not reproducable d.fixed in next 
relese e.cannot be fixed f.request for enhancement
with above all condition is satisfied then they assign bug 
to concerned developer
3.once developer fix the bug then he send to me for retest 
the same bug
4.if the bug is fix then i close the bug
5.if not i will reopen the bug  
and the process repeats

3>compatability testing:testing the application with 
differnt hardware and software configeration is 
compatability testing
eg:my application is eblaze online recovery backup so for 
that my features are tested in different platforms such as 
windows xp,2000,2003,vista home,vista proffesional and with 
diff config such as 256 ram,512 ram,1 gb ram,2 gb ram and 
etc

4>priority:the word priority is associated with scheduling
it is of diff types :blockers,major,minor
severity: the word severity is associated with standards or 
urgency
it is of different types high,medium,low
usualy as a tester i will give whether bug is blocker or 
major or minor
based on that developer will give prominence and fix the 
concerned bug