Conceptual Question About ETL
Dec 18, 2004
Hi,
A simple question but I just want to clarify my understanding:
E = Extract
T = Transform
L = Load
I clearly understand the "E" part which simply means extracting data from the data sources e.g. your OLTP systems or whatever into your Data Mart/ Data Warehouse.
However I am now fully clear as to what do the "T" and the "L" really represent.
Does the "T" (Transform) represent the processing that we do in our Datamart/DW (which some also refer to as the 'Staging Area') or ???
Can you please help be conceptually be clear about this?
Does the "L" (Load) part represent the process of updating our dimensions and Cubes?
I'll appreciate your reply. Thanks
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May 11, 2004
Hi,
I want to use functions like Standard Deviation, Variance, and other forms of these (StdDevp, Varp) but am not clear about what these really do. All I know is that if I am clear about these functions, I can really put these to good use. BTW, maybe there are many more functions in addition to the one's that I have listed??
Can you kindly assist me with a mini example in understanding what these functions do?
Suppose I have the Total and Average of orders. How can these functions be put to use? Kindly help me out if you can come up with a better example.
I'll be grateful for your help.
Many TIA.
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Jul 23, 2005
I think cursors might help me, but I'm not sure. I'm looking for ideason how to solve a problem I have.Consider two tables, one table contains student information (very wide100 fields) , the other historical changes of the student information,(narrow, just fields that record changes).As an example Table one has STUDENT_ID, STUDENT_MAJOR, STUDENT_NAME,RECORD_DT and has one student in it.Table two contains STUDENT_ID, STUDENT_MAJOR , CHANGE_DT and contains 2records, since the student changed their major 2 times.I want to end up with a table the contains 3 rows, the 2 changes to theMajor and the current student record. I want each row to be complete.Everything that I have tried (joins, outer joins, union) I end up withsome field being null (in my example, the STUDENT_NAME would on be inthe original row, and null for the two changes)I know this is pretty vague, but I am wondering if this is a place touse CURSORS?(Some of you may recognize this as a type 2 dimension or slowlychanging dimension as used in a data warehouse, which it is. I need tobuild up my historical changes to I can feed it to my warehouse. I havethe current student record, and all the descreet changes made to thestudent.)TIARob
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