Final Exam Review Spring 2004: Questions on Databases


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Final Exam Review Spring 2004: Questions on Databases

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Questions and Answers?

well-designed relational databases have information stored in tables, the columns in those tables are names, and rows in those tables are related. Relational databases might have joins that use hash tables to request information from another database.
SQL (258)is the common language for maniulation and creation of databases. It is JES' equivalent of a for loop.
a join (256)is when multiple tables (hash tables work best) are used to request a query.

Karin Bowman

SQL doesn't have anything to do with a for loop. Hash tables don't necessarily have anything to do with joins. Mark Guzdial

Ok, I don't know where I got the for loop bit from. Sorry about that.

1Name some char. of well-designed rel. databases: column are names, rows of data are assumed 2 b related
2What is SQL? Structured Query Language used 2 manipulate and query databases.
3What is a join?multiple tables 2 answer a query ( a request 4 info from a database). works best w/ simple tables, only 1 relation / row
Mireille Murad

Mireille, can you say something about HOW a join works? What does it do? Mark Guzdial

multiple tables with interconnecting information are used to collect information by using…
kenny

here's some answers I have. Hope it helps. Kyla LeCroy
2. What is SQL? It’s stands for Structured Query Langauge which is used to manipulate and query databases.
3. What is a join? Using multiple tables to answer a query (a request for information from a database). Database joins work best if the tables are kept simple, where there is only a single relation per row.

Yeah, but I'm still looking for HOW a join works. Can you merge any two tables? What's necessary for a join to work? Mark Guzdial

Joins allow us to pull related information from more than one table. For a join to work it is necessary for the tables you are merging to have overlapping relationships. In the book they use the example of finding a picture and student name from three different tables. To do this you search the first database for the student name. That row gives you the relationship between student name and ID number. Then the second table is searched for that ID number giving you the relationship between the ID number and the picture ID. Finally, the third table is searched giving you the relationship between picture ID and picture. Then, the picture and student name are returned. So, joins search tables in databases with overlapping information in order to return the results of a certain query. I don't know if this really explains what you were looking for on HOW a join works or what's necessary for it to work. Was this kind of what you were looking for?
Heather Symon

Heather, that's very nice. The main idea is the "overlapping relationships" as you call it. Mark Guzdial

If anyone has used the relationship function in Microsoft Access, that could help as a visual reference. Connecting tables through a key cell that coexists in both tables. If I am wrong just delete this off the page and I'll go watch star wars in my wookie costume. My $.02

Thomas Sobeck

Thomas, you're right, but even if you're wrong, I would never sentence you to watching Star Wars in a Wookie costume! :-) Mark Guzdial

I used to have Ewok pajamas when I was a little kid. I liked to run around and say "Yub yub." I was one cute little kid. I still am, so they tell me. Jonathan Laing

haha what is this story time?

i dunno, but it's funny at 2am!

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Sp2004 Final Exam Review last edited on 26 April 2004 at 3:49 pm by guzdial2.cc.gatech.edu