Re: Select from multiple tables
Karl DeSaulniers <[email protected]>
| Newsgroups | gmane.comp.php.database |
|---|---|
| Message-ID | <[email protected]> |
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 > <[email protected]>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 <[email protected]> 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 <[email protected]> >>> 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 <[email protected]> >> 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 >>>>> >> >> -- >> PHP Database Mailing List (http://www.php.net/) >> To unsubscribe, visit: http://www.php.net/unsub.php >> >> Karl DeSaulniers Design Drumm http://designdrumm.com -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php