Re: Parent/Child - Linked List
See the piece on trees at www.artfulsoftware.com. It goes into several variations of how to handle hierarchies. HTH, -- Arthur Cell: 647.710.1314 Prediction is difficult, especially of the future. -- Neils Bohr
Re: Parent/Child - Linked List
On Mon, Jan 16, 2012 at 1:52 PM, bruce badoug...@gmail.com wrote: Hey Authur. Should have been more clear. I've looked over a number of sites. And with the exception of the the articles that talk about using the Nested List approach, nowhere did I find data on how to get a complete list of the child descendants of a given 'root'/top item from the parent/child TBL. Chunks of code/pointers would be seriously useful. Thanks On Mon, Jan 16, 2012 at 12:18 PM, Arthur Fuller fuller.art...@gmail.com wrote: See the piece on trees at www.artfulsoftware.com. It goes into several variations of how to handle hierarchies. HTH, -- Arthur Cell: 647.710.1314 Prediction is difficult, especially of the future. -- Neils Bohr -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql
Re: Parent/Child - Linked List
On 1/16/2012 12:53 PM, bruce wrote: On Mon, Jan 16, 2012 at 1:52 PM, brucebadoug...@gmail.com wrote: Hey Authur. Should have been more clear. I've looked over a number of sites. And with the exception of the the articles that talk about using the Nested List approach, nowhere did I find data on how to get a complete list of the child descendants of a given 'root'/top item from the parent/child TBL. Look again, eg listings 7 through 7d in http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html. PB - Chunks of code/pointers would be seriously useful. Thanks On Mon, Jan 16, 2012 at 12:18 PM, Arthur Fullerfuller.art...@gmail.com wrote: See the piece on trees at www.artfulsoftware.com. It goes into several variations of how to handle hierarchies. HTH, -- Arthur Cell: 647.710.1314 Prediction is difficult, especially of the future. -- Neils Bohr -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql
Re: Parent/Child - Linked List
hi Peter. Sorry.. Been looking at this for awhile. In the sample data/tbl I provided, it has two top level root/parents. Ie, I have two entries that don't have a parentID. I use 0 to be null. The items are (0,1), and (0,8). The (0,1) item, has a number of descendants. The (0,8) only has a single descendant. For my app, I'm going to have a number of top level items, and they're each going to have a number of descendants, where I don't know the number of descendant rows, or the number of actual descendants. But either way, once I get the descendant list, I still need some way of linking the childID of the descendant to the linked ID of the statusTBL so I can get the status of the childID/app. And like I said, I'm not quite sure how to proceed in an efficient manner on this. Thanks On Mon, Jan 16, 2012 at 4:08 PM, Peter Brawley peter.braw...@earthlink.net wrote: On 1/16/2012 2:08 PM, bruce wrote: Hi Peter. Not a mysql guru... so I've never used stored procedures/sub-queries.. But it sort of makes sense. What I'm really trying to get is to be able to take a test table like below LOCK TABLES `parentChildTBL` WRITE; /*!4 ALTER TABLE `parentChildTBL` DISABLE KEYS */; INSERT INTO `parentChildTBL` VALUES (0,1,1), (1,2,2), (1,3,3), (1,4,4), (2,5,5), (2,6,6), (2,7,7), (0,8,8), (8,9,9); UNLOCK TABLES; and to be able to generate the child/descendant list of the top two/2 items (1,8) I don't understand top two(1,8). In general a non-procedural query of n recursion levels requires n-1 joins. If the number of recursive references is unknown beforehand, the only way to query the tree is via a stored procedure. PB - if I only have a single top level item.. and can do a left join.. but I'm not sure how to accomplish this with two top items, unless I take a look at the approach you provided. I'm looking at being able to compare a 'status' from a linked tbl, that links on the childID... thanks On Mon, Jan 16, 2012 at 2:33 PM, Peter Brawley peter.braw...@earthlink.net wrote: On 1/16/2012 12:53 PM, bruce wrote: On Mon, Jan 16, 2012 at 1:52 PM, brucebadoug...@gmail.com wrote: Hey Authur. Should have been more clear. I've looked over a number of sites. And with the exception of the the articles that talk about using the Nested List approach, nowhere did I find data on how to get a complete list of the child descendants of a given 'root'/top item from the parent/child TBL. Look again, eg listings 7 through 7d in http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html. PB - Chunks of code/pointers would be seriously useful. Thanks On Mon, Jan 16, 2012 at 12:18 PM, Arthur Fullerfuller.art...@gmail.com wrote: See the piece on trees at www.artfulsoftware.com. It goes into several variations of how to handle hierarchies. HTH, -- Arthur Cell: 647.710.1314 Prediction is difficult, especially of the future. -- Neils Bohr -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql
Re: Parent/Child - Linked List
On 1/16/2012 4:14 PM, bruce wrote: hi Peter. Sorry.. Been looking at this for awhile. In the sample data/tbl I provided, it has two top level root/parents. Ie, I have two entries that don't have a parentID. I use 0 to be null. Mistake. use Null. The items are (0,1), and (0,8). Then the table has two trees. See Multiple trees in one table at http://www.artfulsoftware.com/infotree/queries.php. PB - The (0,1) item, has a number of descendants. The (0,8) only has a single descendant. For my app, I'm going to have a number of top level items, and they're each going to have a number of descendants, where I don't know the number of descendant rows, or the number of actual descendants. But either way, once I get the descendant list, I still need some way of linking the childID of the descendant to the linked ID of the statusTBL so I can get the status of the childID/app. And like I said, I'm not quite sure how to proceed in an efficient manner on this. Thanks On Mon, Jan 16, 2012 at 4:08 PM, Peter Brawley peter.braw...@earthlink.net wrote: On 1/16/2012 2:08 PM, bruce wrote: Hi Peter. Not a mysql guru... so I've never used stored procedures/sub-queries.. But it sort of makes sense. What I'm really trying to get is to be able to take a test table like below LOCK TABLES `parentChildTBL` WRITE; /*!4 ALTER TABLE `parentChildTBL` DISABLE KEYS */; INSERT INTO `parentChildTBL` VALUES (0,1,1), (1,2,2), (1,3,3), (1,4,4), (2,5,5), (2,6,6), (2,7,7), (0,8,8), (8,9,9); UNLOCK TABLES; and to be able to generate the child/descendant list of the top two/2 items (1,8) I don't understand top two(1,8). In general a non-procedural query of n recursion levels requires n-1 joins. If the number of recursive references is unknown beforehand, the only way to query the tree is via a stored procedure. PB - if I only have a single top level item.. and can do a left join.. but I'm not sure how to accomplish this with two top items, unless I take a look at the approach you provided. I'm looking at being able to compare a 'status' from a linked tbl, that links on the childID... thanks On Mon, Jan 16, 2012 at 2:33 PM, Peter Brawleypeter.braw...@earthlink.net wrote: On 1/16/2012 12:53 PM, bruce wrote: On Mon, Jan 16, 2012 at 1:52 PM, brucebadoug...@gmail.com wrote: Hey Authur. Should have been more clear. I've looked over a number of sites. And with the exception of the the articles that talk about using the Nested List approach, nowhere did I find data on how to get a complete list of the child descendants of a given 'root'/top item from the parent/child TBL. Look again, eg listings 7 through 7d in http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html. PB - Chunks of code/pointers would be seriously useful. Thanks On Mon, Jan 16, 2012 at 12:18 PM, Arthur Fullerfuller.art...@gmail.com wrote: See the piece on trees at www.artfulsoftware.com. It goes into several variations of how to handle hierarchies. HTH, -- Arthur Cell: 647.710.1314 Prediction is difficult, especially of the future. -- Neils Bohr -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql
