Re: Please help! Recursive loop in JSP
I don't think so I have been using it since version 7. Give it a try on your instance. Happy hunting. Scott. "Chen, Gin" cc: Sent by: A Subject: Re: Please help! Recursive loop in JSP mailing list about Java Server Pages specification and reference . 11/13/01 03:01 PM Please respond to A mailing list about Java Server Pages specification and reference Thats pretty cool Scott. But its only available using Oracle 9i. :P Heres a link to it for those too lazy to look it up :) http://download-west.oracle.com/otndoc/oracle9i/901_doc/server.901/a90125/qu eries2.htm -Tim -Original Message- From: Scott Watson [mailto:[EMAIL PROTECTED]] Sent: Tuesday, November 13, 2001 2:51 PM To: [EMAIL PROTECTED] Subject: Re: Please help! Recursive loop in JSP Joe, You can get more information at otn.oracle.com or do a search on google. I believe these type of queries are called Hierarchical Queries. Your DBA should be able to provide you with more information. The level pseudo column is what tells you how far from the root this record can be found. Scott. Joe Cheng <[EMAIL PROTECTED]>To: [EMAIL PROTECTED] Sent by: A cc: mailing list Subject: Re: Please help! Recursive loop in JSP about Java Server Pages specification and reference . 11/13/01 11:00 AM Please respond to A mailing list about Java Server Pages specification and reference >> If you are selecting data from a database and that database happens to be Oracle look at the connect by clause. It does everything you are looking for. << that's really interesting, I've never heard of "connect by". can you or Ross provide more detail, i.e. what does the resulting recordset look like? === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
I was wrong. Its also in Oracle 8i. :P http://technet.oracle.com/docs/products/oracle8i/doc_library/817_doc/server. 817/a85397.pdf -Tim -Original Message- From: Chen, Gin [mailto:[EMAIL PROTECTED]] Sent: Tuesday, November 13, 2001 3:02 PM To: [EMAIL PROTECTED] Subject: Re: Please help! Recursive loop in JSP Thats pretty cool Scott. But its only available using Oracle 9i. :P Heres a link to it for those too lazy to look it up :) http://download-west.oracle.com/otndoc/oracle9i/901_doc/server.901/a90125/qu eries2.htm -Tim -Original Message- From: Scott Watson [mailto:[EMAIL PROTECTED]] Sent: Tuesday, November 13, 2001 2:51 PM To: [EMAIL PROTECTED] Subject: Re: Please help! Recursive loop in JSP Joe, You can get more information at otn.oracle.com or do a search on google. I believe these type of queries are called Hierarchical Queries. Your DBA should be able to provide you with more information. The level pseudo column is what tells you how far from the root this record can be found. Scott. Joe Cheng <[EMAIL PROTECTED]>To: [EMAIL PROTECTED] Sent by: A cc: mailing list Subject: Re: Please help! Recursive loop in JSP about Java Server Pages specification and reference . 11/13/01 11:00 AM Please respond to A mailing list about Java Server Pages specification and reference >> If you are selecting data from a database and that database happens to be Oracle look at the connect by clause. It does everything you are looking for. << that's really interesting, I've never heard of "connect by". can you or Ross provide more detail, i.e. what does the resulting recordset look like? === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
Thats pretty cool Scott. But its only available using Oracle 9i. :P Heres a link to it for those too lazy to look it up :) http://download-west.oracle.com/otndoc/oracle9i/901_doc/server.901/a90125/qu eries2.htm -Tim -Original Message- From: Scott Watson [mailto:[EMAIL PROTECTED]] Sent: Tuesday, November 13, 2001 2:51 PM To: [EMAIL PROTECTED] Subject: Re: Please help! Recursive loop in JSP Joe, You can get more information at otn.oracle.com or do a search on google. I believe these type of queries are called Hierarchical Queries. Your DBA should be able to provide you with more information. The level pseudo column is what tells you how far from the root this record can be found. Scott. Joe Cheng <[EMAIL PROTECTED]>To: [EMAIL PROTECTED] Sent by: A cc: mailing list Subject: Re: Please help! Recursive loop in JSP about Java Server Pages specification and reference . 11/13/01 11:00 AM Please respond to A mailing list about Java Server Pages specification and reference >> If you are selecting data from a database and that database happens to be Oracle look at the connect by clause. It does everything you are looking for. << that's really interesting, I've never heard of "connect by". can you or Ross provide more detail, i.e. what does the resulting recordset look like? === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
Joe, You can get more information at otn.oracle.com or do a search on google. I believe these type of queries are called Hierarchical Queries. Your DBA should be able to provide you with more information. The level pseudo column is what tells you how far from the root this record can be found. Scott. Joe Cheng <[EMAIL PROTECTED]>To: [EMAIL PROTECTED] Sent by: A cc: mailing list Subject: Re: Please help! Recursive loop in JSP about Java Server Pages specification and reference . 11/13/01 11:00 AM Please respond to A mailing list about Java Server Pages specification and reference >> If you are selecting data from a database and that database happens to be Oracle look at the connect by clause. It does everything you are looking for. << that's really interesting, I've never heard of "connect by". can you or Ross provide more detail, i.e. what does the resulting recordset look like? === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
What do you mean by multiple vectors?
I have a program that uses a hashtable that stores a vector as objects.
Think of this as categories and items.
If I have a grocery store. I might have categories of
"Canned Foods", "Vegetables", "Meats".
And items inside of them
I have vectors for all the items under one category
so my vector for Canned Foods will look something like:
Beans | Peaches | Corn
I have a hashtable to store these keyed by category name:
Hashtable:
Key Value
"Canned Food" Vector( Beans | Peaches | Corn )
"Vegetables"Vector( Spinach | Broccoli | Tomato )
"Meats" Vector( Chicken | Veal | Pork )
So my program would do something like: (Not complete and not tested)
private Hashtable myStore;
public void createStore()
{
//database code: not best way to do db code and not
complete!
rCategories = stmt.execute("select category_name from
categories");
while( rCategories.next() )
{
String category = rCategories.getString(1);
Vector vItems = new Vector();
//database code: not best way to do db code and not
complete!
rItems = stmt.execute(
"select item_name from items where
category_name='"+ category +"'");
while( rItems.next() )
{
vItems.add( rs.getString(1) );
}
myStore.put( category, vItems );
}
}
-Tim
-Original Message-
From: Kenny Dao [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, November 13, 2001 11:10 AM
To: [EMAIL PROTECTED]
Subject: Re: Please help! Recursive loop in JSP
Hi
does any know or have an example of how to store
multiple vectors inside a hashtable?
thank
Ken
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Re: Please help! Recursive loop in JSP
Hi does any know or have an example of how to store multiple vectors inside a hashtable? thank Ken > http://archives.java.sun.com/jsp-interest.html > http://java.sun.com/products/jsp/faq.html > http://www.esperanto.org.nz/jsp/jspfaq.jsp > http://www.jguru.com/faq/index.jsp > http://www.jspinsider.com __ Do You Yahoo!? Find the one for you at Yahoo! Personals http://personals.yahoo.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
>> If you are selecting data from a database and that database happens to be Oracle look at the connect by clause. It does everything you are looking for. << that's really interesting, I've never heard of "connect by". can you or Ross provide more detail, i.e. what does the resulting recordset look like? === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
If you are selecting data from a database and that database happens to be Oracle look at the connect by clause. It does everything you are looking for. eg select name, id, level from yourtable where start with id=0/* or put whatever id you want to start looking from */ connect by prior id = parent_id ; Scott. Frank Mancini cc: Sent by: A Subject: Re: Please help! Recursive loop in JSP mailing list about Java Server Pages specification and reference . 11/12/01 06:16 PM Please respond to A mailing list about Java Server Pages specification and reference Thanks Joe, ya I want more info. I think we will choose the narrower and deeper family. Let me know if you have anymore ideas. >From: Joe Cheng <[EMAIL PROTECTED]> >Reply-To: A mailing list about Java Server Pages specification and >reference <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED] >Subject: Re: Please help! Recursive loop in JSP >Date: Mon, 12 Nov 2001 17:21:24 -0500 > >I had to do this once... fun problem. > >First of all, forget about doing it "in JSP"... you should use Java classes >for this. > >Two ways to do it, IMO. If you have a large and flat dataset, i.e. many >records in the table but no trees that go more than a few generations deep, >you can have a method in the Person object of signature: > public Person[] getAllChildren() >that queries for all the children, and calls getAllChildren() on them, and >adds the results into some kind of vector. However, that will result in >many calls to the database because each getAllChildren() call will cost you >a query. > >If the dataset is narrower and deeper, i.e. a few very deep families, you >can create a method that loads up all the data in one query and then >constructs the objects using a method similar to the above. The advantage >of this is that you only have to run the query once; the disadvantages are >that you have loaded all this data that may or may not be used. > >Let me know if you need more detail... > >-jmc > >-Original Message- >From: Frank Mancini [mailto:[EMAIL PROTECTED]] >Sent: Monday, November 12, 2001 5:04 PM >To: [EMAIL PROTECTED] >Subject: Please help! Recursive loop in JSP > > >I have a recursive looping problem here. > >For example, say I have this table > >id, name, parent > >1,john,4 >2,bill,3 >3,cathy,4 >4,jackie,0 >5,jeff,4 >6,joe,7 >7,amy,0 > >Essentially, > >jackie doesn't have a parent, but has john, jeff and cathy as children. >bill >is the child of cathy and thus jackies grandchild. > > >How would I do this query such that I say I want to see all the children >(including everyone below him/her) below, say jackie...this is really a >self >join to oneself with an unknown number of levels below. > >How would I do this in jsp do display all of jackies relatives below her? > >_ >Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp > > === >To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff >JSP-INTEREST". >For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST >DIGEST". >Some relevant FAQs on JSP/Servlets can be found at: > > http://archives.java.sun.com/jsp-interest.html > http://java.sun.com/products/jsp/faq.html > http://www.esperanto.org.nz/jsp/jspfaq.jsp > http://www.jguru.com/faq/index.jsp > http://www.jspinsider.com > > === >To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff >JSP-INTEREST". >For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST >DIGEST". >Some relevant FAQs on JSP/Servlets can be found at: > > http://archives.java.sun.com/jsp-interest.html > http://java.sun.com/products/jsp/faq.html > http://www.esperanto.org.nz/jsp/jspfaq.jsp > http://www.jguru.com/faq/index.jsp > http://www.jspinsider.com _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp === To unsubscribe: mailto [EMAIL PROTECTED] with body:
Re: Please help! Recursive loop in JSP
1. The easy way if you are using an oracle database, this gets them all in
one query
select name
from table
start with id = ?
connect by parent = prior id
2. use a stack
Brief example...
class Person {
int id;
String name;
Person(int id, String name) {
this.id = id;
this.name = name;
}
}
// Create node to start with
Person root = new Person(4, "Jackie");
Stack stack = new Stack();
// Place starting node on stack
stack.push(root);
Connection con = ... get connection here
PreparedStatement ps = con.prepareStatement("select id, name from table
where parent = ?");
do {
Person current = (Person) stack.pop();
// Print current item on stack
out.println("" + current.name + "");
// Set parent to look for
ps.setInt(1, person.id);
// Get children
ResultSet rs = ps.executeQuery();
while (rs.next()) {
// Place children on stack
stack.push(new Person(rs.getInt(1), rs.getString(2)));
}
rs.close();
} while(!stack.isEmpty()); // Continue as long as there are more children
ps.close();
con.close();
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Re: Please help! Recursive loop in JSP
1. The easy way if you are using an oracle database, this gets them all in one
query
select name
from table
start with id = ?
connect by parent = prior id
2. use a stack
Brief example...
class Person {
int id;
String name;
Person(int id, String name) {
this.id = id;
this.name = name;
}
}
// Create node to start with
Person root = new Person(4, "Jackie");
Stack stack = new Stack();
// Place starting node on stack
stack.push(root);
Connection con = ... get connection here
PreparedStatement ps = con.prepareStatement("select id, name from table =
where parent = ?");
do {
Person current = (Person) stack.pop();
// Print current item on stack
out.println("" + current.name + "");
// Set parent to look for
ps.setInt(1, person.id);
// Get children
ResultSet rs = ps.executeQuery();
while (rs.next()) {
// Place children on stack
stack.push(new Person(rs.getInt(1), rs.getString(2)));
}
rs.close();
} while(!stack.isEmpty()); // Continue as long as there are more children
ps.close();
con.close();
-Original Message-
From:Frank Mancini [EMAIL PROTECTED]
Sent:Mon, 12 Nov 2001 14:04:14 -0800
To: [EMAIL PROTECTED]
Subject: Please help! Recursive loop in JSP
I have a recursive looping problem here.
For example, say I have this table
id, name, parent
1,john,4
2,bill,3
3,cathy,4
4,jackie,0
5,jeff,4
6,joe,7
7,amy,0
Essentially,
jackie doesn't have a parent, but has john, jeff and cathy as children. bill
is the child of cathy and thus jackies grandchild.
How would I do this query such that I say I want to see all the children
(including everyone below him/her) below, say jackie...this is really a self
join to oneself with an unknown number of levels below.
How would I do this in jsp do display all of jackies relatives below her?
_
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp
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Re: Please help! Recursive loop in JSP
Thanks Joe, ya I want more info. I think we will choose the narrower and deeper family. Let me know if you have anymore ideas. >From: Joe Cheng <[EMAIL PROTECTED]> >Reply-To: A mailing list about Java Server Pages specification and >reference <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED] >Subject: Re: Please help! Recursive loop in JSP >Date: Mon, 12 Nov 2001 17:21:24 -0500 > >I had to do this once... fun problem. > >First of all, forget about doing it "in JSP"... you should use Java classes >for this. > >Two ways to do it, IMO. If you have a large and flat dataset, i.e. many >records in the table but no trees that go more than a few generations deep, >you can have a method in the Person object of signature: > public Person[] getAllChildren() >that queries for all the children, and calls getAllChildren() on them, and >adds the results into some kind of vector. However, that will result in >many calls to the database because each getAllChildren() call will cost you >a query. > >If the dataset is narrower and deeper, i.e. a few very deep families, you >can create a method that loads up all the data in one query and then >constructs the objects using a method similar to the above. The advantage >of this is that you only have to run the query once; the disadvantages are >that you have loaded all this data that may or may not be used. > >Let me know if you need more detail... > >-jmc > >-Original Message- >From: Frank Mancini [mailto:[EMAIL PROTECTED]] >Sent: Monday, November 12, 2001 5:04 PM >To: [EMAIL PROTECTED] >Subject: Please help! Recursive loop in JSP > > >I have a recursive looping problem here. > >For example, say I have this table > >id, name, parent > >1,john,4 >2,bill,3 >3,cathy,4 >4,jackie,0 >5,jeff,4 >6,joe,7 >7,amy,0 > >Essentially, > >jackie doesn't have a parent, but has john, jeff and cathy as children. >bill >is the child of cathy and thus jackies grandchild. > > >How would I do this query such that I say I want to see all the children >(including everyone below him/her) below, say jackie...this is really a >self >join to oneself with an unknown number of levels below. > >How would I do this in jsp do display all of jackies relatives below her? > >_ >Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp > >=== >To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff >JSP-INTEREST". >For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST >DIGEST". >Some relevant FAQs on JSP/Servlets can be found at: > > http://archives.java.sun.com/jsp-interest.html > http://java.sun.com/products/jsp/faq.html > http://www.esperanto.org.nz/jsp/jspfaq.jsp > http://www.jguru.com/faq/index.jsp > http://www.jspinsider.com > >=== >To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff >JSP-INTEREST". >For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST >DIGEST". >Some relevant FAQs on JSP/Servlets can be found at: > > http://archives.java.sun.com/jsp-interest.html > http://java.sun.com/products/jsp/faq.html > http://www.esperanto.org.nz/jsp/jspfaq.jsp > http://www.jguru.com/faq/index.jsp > http://www.jspinsider.com _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
Title: RE: Please help! Recursive loop in JSP I meant to say use java equivalent, not jsp equivalent because a bean should be used like Chris just mentioned... -Original Message-From: Jean-Francois Pinero [mailto:[EMAIL PROTECTED]]Sent: Monday, November 12, 2001 5:29 PMTo: [EMAIL PROTECTED]Subject: Re: Please help! Recursive loop in JSP I haven't tested the code and wrote it in less than 10 minutes so you might want to try it out first but solution should be along one of those lines... Code below is probably a combination of JSP, asp, vb and java so use jsp equivalent of course. :) pseudocode: myId = 4 (jackie) myParent = 9 (garbage for the first pass) print parent's name (jackie in this case) call recurseMe(myId, myParent) ... *** function recurseMe(myId, myParent) While myParent != 0 conn.execute "select name from table where parent = " + myId (this is your recordset of john, cathy and jeff on the first pass around) while not recordset.eof print out name (this is the child's name) myParent = recordset.parent recurse(recordset.id, recordset.parent) recordset.moveNext() end of while end of while end of recurseMe *** -Original Message- From: Frank Mancini [mailto:[EMAIL PROTECTED]] Sent: Monday, November 12, 2001 5:04 PM To: [EMAIL PROTECTED] Subject: Please help! Recursive loop in JSP I have a recursive looping problem here. For example, say I have this table id, name, parent 1,john,4 2,bill,3 3,cathy,4 4,jackie,0 5,jeff,4 6,joe,7 7,amy,0 Essentially, jackie doesn't have a parent, but has john, jeff and cathy as children. bill is the child of cathy and thus jackies grandchild. How would I do this query such that I say I want to see all the children (including everyone below him/her) below, say jackie...this is really a self join to oneself with an unknown number of levels below. How would I do this in jsp do display all of jackies relatives below her? _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
Easiest way to do this is just to set up a recursive method call to go through each level in the tree. Effectively you're just doing a tree traversal, and can apply all the standard algorithms to this: your nodes are each of the people, and can be picked out using an appropriate SQL query (e.g. SELECT name FROM People WHERE parent = 4). You can build this query for each recursive call, modifying the WHERE clause appropriately. The problem with this approach is that you can end up with a shedload of database connections going on, and if the tree is deep or broad you'll suffer from a hell of a slowdown related to having to initiate a query for every single person. You can optimise this by using more complicated WHERE clauses on your SQL to select everyone at a given level meeting the appropriate criteria, thereby limiting the number of recursive calls to h (where h is the height of the tree). You may also want to maintain a list of all the nodes you have already processed to check for the a mistake in the data that leads to a cyclic dependency (e.g. mary is johns mother, mary is johns daughter). Your data shouldn't have these in it, but it's a good idea to check to make sure or you risk crashing the server in a big ol' recursive loop. There are further ways to optimise the queries (such as unrolling your recursion into a loop), but unless this is going to be a real heavy load situation you're likely to be better off going for code readibility and maintainability. As far as doing this in JSP is concerned, you should put the code to do the actual recursive search into a bean and simply format its output with appropriate JSP. Hope that helps, Chris Tucker -Original Message- From: A mailing list about Java Server Pages specification and reference [mailto:[EMAIL PROTECTED]]On Behalf Of Frank Mancini Sent: Monday, November 12, 2001 2:04 PM To: [EMAIL PROTECTED] Subject: Please help! Recursive loop in JSP I have a recursive looping problem here. For example, say I have this table id, name, parent 1,john,4 2,bill,3 3,cathy,4 4,jackie,0 5,jeff,4 6,joe,7 7,amy,0 Essentially, jackie doesn't have a parent, but has john, jeff and cathy as children. bill is the child of cathy and thus jackies grandchild. How would I do this query such that I say I want to see all the children (including everyone below him/her) below, say jackie...this is really a self join to oneself with an unknown number of levels below. How would I do this in jsp do display all of jackies relatives below her? _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
Title: RE: Please help! Recursive loop in JSP I haven't tested the code and wrote it in less than 10 minutes so you might want to try it out first but solution should be along one of those lines... Code below is probably a combination of JSP, asp, vb and java so use jsp equivalent of course. :) pseudocode: myId = 4 (jackie) myParent = 9 (garbage for the first pass) print parent's name (jackie in this case) call recurseMe(myId, myParent) ... *** function recurseMe(myId, myParent) While myParent != 0 conn.execute "select name from table where parent = " + myId (this is your recordset of john, cathy and jeff on the first pass around) while not recordset.eof print out name (this is the child's name) myParent = recordset.parent recurse(recordset.id, recordset.parent) recordset.moveNext() end of while end of while end of recurseMe *** -Original Message- From: Frank Mancini [mailto:[EMAIL PROTECTED]] Sent: Monday, November 12, 2001 5:04 PM To: [EMAIL PROTECTED] Subject: Please help! Recursive loop in JSP I have a recursive looping problem here. For example, say I have this table id, name, parent 1,john,4 2,bill,3 3,cathy,4 4,jackie,0 5,jeff,4 6,joe,7 7,amy,0 Essentially, jackie doesn't have a parent, but has john, jeff and cathy as children. bill is the child of cathy and thus jackies grandchild. How would I do this query such that I say I want to see all the children (including everyone below him/her) below, say jackie...this is really a self join to oneself with an unknown number of levels below. How would I do this in jsp do display all of jackies relatives below her? _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Re: Please help! Recursive loop in JSP
I had to do this once... fun problem. First of all, forget about doing it "in JSP"... you should use Java classes for this. Two ways to do it, IMO. If you have a large and flat dataset, i.e. many records in the table but no trees that go more than a few generations deep, you can have a method in the Person object of signature: public Person[] getAllChildren() that queries for all the children, and calls getAllChildren() on them, and adds the results into some kind of vector. However, that will result in many calls to the database because each getAllChildren() call will cost you a query. If the dataset is narrower and deeper, i.e. a few very deep families, you can create a method that loads up all the data in one query and then constructs the objects using a method similar to the above. The advantage of this is that you only have to run the query once; the disadvantages are that you have loaded all this data that may or may not be used. Let me know if you need more detail... -jmc -Original Message- From: Frank Mancini [mailto:[EMAIL PROTECTED]] Sent: Monday, November 12, 2001 5:04 PM To: [EMAIL PROTECTED] Subject: Please help! Recursive loop in JSP I have a recursive looping problem here. For example, say I have this table id, name, parent 1,john,4 2,bill,3 3,cathy,4 4,jackie,0 5,jeff,4 6,joe,7 7,amy,0 Essentially, jackie doesn't have a parent, but has john, jeff and cathy as children. bill is the child of cathy and thus jackies grandchild. How would I do this query such that I say I want to see all the children (including everyone below him/her) below, say jackie...this is really a self join to oneself with an unknown number of levels below. How would I do this in jsp do display all of jackies relatives below her? _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
Please help! Recursive loop in JSP
I have a recursive looping problem here. For example, say I have this table id, name, parent 1,john,4 2,bill,3 3,cathy,4 4,jackie,0 5,jeff,4 6,joe,7 7,amy,0 Essentially, jackie doesn't have a parent, but has john, jeff and cathy as children. bill is the child of cathy and thus jackies grandchild. How would I do this query such that I say I want to see all the children (including everyone below him/her) below, say jackie...this is really a self join to oneself with an unknown number of levels below. How would I do this in jsp do display all of jackies relatives below her? _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp === To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant FAQs on JSP/Servlets can be found at: http://archives.java.sun.com/jsp-interest.html http://java.sun.com/products/jsp/faq.html http://www.esperanto.org.nz/jsp/jspfaq.jsp http://www.jguru.com/faq/index.jsp http://www.jspinsider.com
