Re: Select from multiple tables

From: Date: Thu, 01 Mar 2012 07:04:08 +0000
Subject: Re: Select from multiple tables
References: 1 2 3 4 5 6 7  Groups: php.db 
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This is just a stab in the dark and may be in the wrong order. If it does not work I apologize. SELECT s.Title, (SELECT DISTINCT b.Board_id), (SELECT DISTINCT t.type), (SELECT s.School_id AND b.School_id AND t.schoolid AS id ) FROM school s, board_entries b, schooltypeentries t WHERE id = 1698 HTW, Best, Karl On Feb 29, 2012, at 11:46 PM, Kranthi Krishna wrote:
Hi all, SELECT DISTINCT s.Title, b.Board_id, t.type FROM school s, board_entries b, schooltypeentries t WHERE s.School_id = 1698 AND b.School_id = 1698 AND t.schoolid = 1698 this SQL query gives me Kendriya Vidyalaya 15 Kick Boxing Kendriya Vidyalaya 15 Karate Kendriya Vidyalaya 32 Kick Boxing Kendriya Vidyalaya 32 Karate as I stated earlier. Now using php.net/array_search php.net/foreach and php.net/mysql_fetch_assoc I can easily convert that into array
    name => 'Kendriya Vidyalaya'
    board_id => array
         1 => 15
         2 => 32
    type => array
         1 => 'Kick Boxing'
         2 => 'Karate'
I am wondering if there is a better way. For example if I am able to get something like
Kendriya Vidyalaya 	15 	    Kick Boxing
NULL                	NULL    Karate
NULL                	32 	    NULL
NULL                	NULL    NULL
I can use php.net/is_null instead of php.net/array_search I dont think this problem is specific to me. Please suggest some best practices in this case. Kranthi. http://goo.gl/e6t3 On 1 March 2012 10:25, Karl DeSaulniers <karl@designdrumm.com> wrote:
Try DISTINCT On Feb 29, 2012, at 10:28 PM, Amit Tandon wrote:
Dear Kranthi You have to be clear what you decide especially when you are getting multiple rows. To get just a single row you can use LIMIT clause. But it would return only one row. Now you have to decide which row. So i think you decide on what you require and see how can you uniquely identify that row ============ regds amit "The difference between fiction and reality? Fiction has to make sense." On Thu, Mar 1, 2012 at 9:45 AM, Kranthi Krishna <kranthi117@gmail.com>wrote:
Hi, The examples I saw were regarding cartesian join not inner join. I will read about inner joins. Also, the example i mentioned seems to be a mistake. Both school and type will not be similar at the same time Kranthi. http://goo.gl/e6t3 On 1 March 2012 09:26, Kranthi Krishna <kranthi117@gmail.com> wrote:
Hi, Thanks for the input. I have seen some tutorials on joins, they all suggest that MySql returns multiple rows For example -------------------------- School | Board 1 -------------------------- School | Board 1 ------------------------- Now if I have another one-to-many relation ----------------------------------- School | Board 1 | Type 1 ----------------------------------- School | Board 1 | Type 2 ----------------------------------- School | Board 2 | Type 1 ----------------------------------- School | Board 2 | Type 2 ------------------------------------ Using UNIQUE or something similar (like php.net/array_search ) causes problems when Type 1 = Type 2 etc. Kranthi. http://goo.gl/e6t3 On 29 February 2012 19:43, Michael Stowe <mikegstowe@gmail.com> wrote:
Select table1.item1, table2.item1 from table1 inner join table2 on
table1.key = table2.foreignKey Where...
You can also utilize left and right join to get data if there isn't a
direct match (ie customer may not have ordered anything so you want to do a left join on orders as there may not be any order data but you still want to get the customer info).
Hope that helps, Mike Sent from my iPhone On Feb 29, 2012, at 8:01 AM, Kranthi Krishna <kranthi117@gmail.com
wrote:
Hi all, Say I have an object like array schoolName => string board => array
      string
      string
I generally create two MySql tables schools: id PRIMARY KEY, SchoolName boards: id FOREGIN KEY refers Table A(id), board and then do two selects. The problem is that, the number of selects increase as the number of one-to-many relationships increase. Is there a better way to do this ? I have to extend an existing code so I cannot use any libraries like doctrine Kranthi. http://goo.gl/e6t3 -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
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