2nf

robasc · #1 (**permalink**) 03-19-07, 00:31

I am trying to understand 2NF, Is there any way to put the data below in
2NF:

http://www.mylabserver.com/226_1/arn...5_1dataImg.gif

Thank you

pootle flump · #2 (**permalink**) 03-19-07, 04:10

Are you sure you don't mean you have an assignment to get that to 2 NF?

What have you got so far? And what do you understand to be 2NF?

r937 · #3 (**permalink**) 03-19-07, 05:01

Quote:

Originally Posted by robasc

I am trying to understand 2NF, Is there any way to put the data below in
2NF:

probably the first thing you should do is put that data into 1NF

only after it's in 1NF, then you can start thinking about 2NF

pootle flump · #4 (**permalink**) 03-19-07, 05:04

Aw.... you spoiled my next post

robasc · #5 (**permalink**) 03-19-07, 06:57

I do understand 1NF, and I see that project and time has produced repeating groups and therefore violates 1NF.

But I do not see how to put this in second normal form:

I do know that emp_id is good enough to determine name and time

emp_id => name, time

but what would project determine or can project be by itself?

I am not really shure I understand 2NF yet?

r937 · #6 (**permalink**) 03-19-07, 07:08

if you understand 1NF, could we see your 1NF design please?

yes, project can be by itself, just like employee can be by itself

robasc · #7 (**permalink**) 03-19-07, 07:26

Here is 1NF:

Code:

EMP_ID    NAME               PROJ_NUM    TIME

ENI-26    SEAN O' BRIAN      30-452-T3    .25
ENI-26    SEAN O' BRIAN      30-457-T3    .40
ENI-26    SEAN O' BRIAN      32-244-T3    .30
ENI-33    AMY GUYE           30-452-T3    .05
ENI-33    AMY GUYE           30-382-TC    .35
ENI-33    AMY GUYE           32-244-T3    .60
ENI-35    STEVE BARANCO      30-452-T3    .15
ENI-35    STEVE BARANCO      31-238-TC    .80
ENI-36    ELIZABETH ROSLYN   35-152-TC    .90
ENI-38    CAROL SHAAF        36-272-TC    .75
ENI-40    ALEX WING          31-238-TC    .20
ENI-40    ALEX WING          31-241-TC    .70

r937 · #8 (**permalink**) 03-19-07, 07:49

excellent

i hope you don't mind, i edited your post to format the display

okay, now, let's think about what 2NF would mean for this table

first of all, what would the PK for this table be?

robasc · #9 (**permalink**) 03-19-07, 10:24

Thanks for editing the code,

the primary key's would be EMP_ID and PROJECT since project seems to uniquely identify each one.

is this correct?

r937 · #10 (**permalink**) 03-19-07, 10:38

yes, EMP_ID and PROJ_NUM would be a candidate key

another would be NAME and PROJ_NUM

another would be EMP_ID and NAME and PROJ_NUM

what is the definition of 2NF?