collections in java
array list algorithm (dynamic array)
map
hashmap ( unordered data)
linkedhashmap ( ordered data)
- treemap are type of linked hash map better in implementation
java iterators for getting next element link
mutable and imutable onbjects link

sql query to find data between an interval.. something like getting data for each week

SELECT MAX( STR_TO_DATE( CONVERT( `PurchaseDt`

USING utf8 ) , '%m-%d-%Y' ) ) AS maxdate, MIN( STR_TO_DATE( CONVERT( `PurchaseDt`

USING utf8 ) , '%m-%d-%Y' ) ) AS mindate

FROM `MemberEarnings`

WHERE STR_TO_DATE( CONVERT( `PurchaseDt`

USING utf8 ) , '%m-%d-%Y' )

BETWEEN STR_TO_DATE( '08-01-2011', '%m-%d-%Y' )

AND STR_TO_DATE( '08-21-2011', '%m-%d-%Y' )

GROUP BY DATE_SUB( STR_TO_DATE( CONVERT( `PurchaseDt`

USING utf8 ) , '%m-%d-%Y' ) , INTERVAL DAYOFWEEK( STR_TO_DATE( CONVERT( `PurchaseDt`

USING utf8 ) , '%m-%d-%Y' ) ) -1

DAY )

scala (new programming language)

data types

def to define objects
val final variables
var which can be changed...

peano Axioms

http://jim-mcbeath.blogspot.com/2008/11/practical-church-numerals-in-scala.html

99 scala problems