A SQL Question

[Telus]

A SQL question

Hi Everybody,
Imagine I have a file with 7 records
and two fields with these data:

Record1--Field1=1--Field2=10:45pm
Record2--Field1=1--Field2=10:46pm
Record3--Field1=2--Field2=10:47pm
Record4--Field1=2--Field2=10:48pm
Record5--Field1=2--Field2=10:49pm
Record6--Field1=1--Field2=10:50pm
Record7--Field1=1--Field2=10:51pm

How can I write a SQL to give me
Records 2,5 and 7, fields 1 and 2?

I mean I sort records base on field 2 then
for each change on field1, I need one record
that can be max or min of field2,
I couldn't use group by because group by consider
all record with field1 value of 1 one group but
I need one record for each changes on record1,

Thank you in advance - Sasan

[Ana C. Dent]

Re: A SQL Question

Telus wrote:

A SQL question
>
Hi Everybody,
Imagine I have a file with 7 records
and two fields with these data:
>
Record1--Field1=1--Field2=10:45pm
Record2--Field1=1--Field2=10:46pm
Record3--Field1=2--Field2=10:47pm
Record4--Field1=2--Field2=10:48pm
Record5--Field1=2--Field2=10:49pm
Record6--Field1=1--Field2=10:50pm
Record7--Field1=1--Field2=10:51pm
>
How can I write a SQL to give me
Records 2,5 and 7, fields 1 and 2?

For what school, course & instructor was this homework assigned?
Based upon what criteria/logic are records 2,5,7 the "correct" answer?

Does the answer change (if so to what?) & why for the following records:

Record1--Field1=1--Field2=10:51pm
Record2--Field1=1--Field2=10:50pm
Record3--Field1=1--Field2=10:46pm
Record4--Field1=1--Field2=10:45pm
Record5--Field1=2--Field2=10:49pm
Record6--Field1=2--Field2=10:47pm
Record7--Field1=2--Field2=10:48pm

[AK]

Re: A SQL Question

"Telus" <sraisdana@l3te chnology.comwro te in message news:<_omNb.131 41$wf1.11109@ed tnps89>...

A SQL question
>
Hi Everybody,
Imagine I have a file with 7 records
and two fields with these data:
>
Record1--Field1=1--Field2=10:45pm
Record2--Field1=1--Field2=10:46pm
Record3--Field1=2--Field2=10:47pm
Record4--Field1=2--Field2=10:48pm
Record5--Field1=2--Field2=10:49pm
Record6--Field1=1--Field2=10:50pm
Record7--Field1=1--Field2=10:51pm
>
How can I write a SQL to give me
Records 2,5 and 7, fields 1 and 2?
>
I mean I sort records base on field 2 then
for each change on field1, I need one record
that can be max or min of field2,
I couldn't use group by because group by consider
all record with field1 value of 1 one group but
I need one record for each changes on record1,
>
Thank you in advance - Sasan

1. add ROWNUM to select list
2. Join adjacent rows, it's easy to do it on ROWNUM
3. add a condition LEFT_SIDE.FIELD 1<>RIGHT_SIDE.F IELD1