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  • Right way to implement a n-to-m related

    - by ThreeFingerMark
    Hello, this is a part from my database structure: Table: Item Columns: ItemID, Title, Content, Price Table: Tag Columns: TagID, Title Table: ItemTag Columns: ItemID, TagID Table: Image Columns: ImageID, Path, Size, UploadDate Table: ItemImage Columns: ItemID, ImageID The items can have more than one image so i have a extra table "Image" and map this images to an items. I see now a problem with this structure. Before i can add Images i must enter an item. My question is now. Is this structure a good way to solve my problem with many images / tags for one item? Thank you

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  • Why are joins bad when considering scalability?

    - by acidzombie24
    Why are joins bad or 'slow'. I know i heard this more then once. I found this quote The problem is joins are relatively slow, especially over very large data sets, and if they are slow your website is slow. It takes a long time to get all those separate bits of information off disk and put them all together again. source I always thought they were fast especially when looking up a PK. Why are they 'slow'?

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  • Updating an object with L2S with ASP.NET MVC

    - by Paul
    Is there an easier way to update an object with L2S other then doing it property by property? This is what I am doing now: Public ActionResult Edit(Object obj) { var objToUpdate = _repository.Single<Object>(o => o.id = obj.id); objToUpdate.Prop1 = obj.Prob1; objToUpdate.Prop2 = obj.Prop2; ... _repository.SubmitChanges(); } I am hoping there is a way to just say objToUpdate = obj then submit the changes??? Any help on this would be appreciated!

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  • what's the performance difference between int and varchar for primary keys

    - by user568576
    I need to create a primary key scheme for a system that will need peer to peer replication. So I'm planning to combine a unique system ID and a sequential number in some way to come up with unique ID's. I want to make sure I'll never run out of ID's, so I'm thinking about using a varchar field, since I could always add another character if I start running out. But I've read that integers are better optimized for this. So I have some questions... 1) Are integers really better optimized? And if they are, how much of a performance difference is there between varchars and integers? I'm going to use firebird for now. But I may switch later. Or possibly support multiple db's. So I'm looking for generalizations, if that's possible. 2) If integers are significantly better optimized, why is that? And is it likely that varchars will catch up in the future, so eventually it won't matter anyway? My varchar keys won't have any meaning, except for the unique system ID part. But I may want to obscure that somehow. Also, I plan to efficiently use all the bits of each character. I don't, for example, plan to code the integer 123 as the character string "123". So I don't think varchars will require more space than integers.

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  • integrating jquery with AJAX using MVC for ddl/html.dropdownlist

    - by needhelp
    the situation: a user on the page in question selects a category from a dropdown which then dynamically populates all the users of that category in a second dropdown beside it. all the data is being retrieved using LinqtoSQL and i was wondering if this can be done a) using html.dropdownlist in a strongly typed view? b) using jquery to trigger the ajax request on selected index change instead of a 'populate' button trigger? sorry i dont have code as what i was trying really wasnt working at all. I am having trouble with how to do it conceptually and programatically! will appreciate any links to examples etc greatly! thanks in advance! EDIT: this is kind of what i was trying to achieve.. first the ViewPage: <script type="text/javascript"> $(document).ready function TypeSearch() { $.getJSON("/Home/Type", null, function(data) { //dont know what to do here }); } </script> <p> <label for="userType">userType:</label> <%= Html.DropDownList("userType") %> <%= Html.ValidationMessage("userType", "*") %> <input type="submit" runat="server" onclick="TypeSearch()" /> <label for="accountNumber">accountNumber:</label> <%= Html.DropDownList("accountNumber") %> <%= Html.ValidationMessage("accountNumber", "*") %> </p> Then home controller action: public ActionResult Type() { string accountType = dropdownvalue; List<Account> accounts = userRep.GetAccountsByType(accountType).ToList(); return Json(accounts); }

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  • sqlite3 date operations when joining two tables in a view?

    - by duncan
    In short, how to add minutes to a datetime from an integer located in another table, in one select statement, by joining them? I have a table P(int id, ..., int minutes) and a table S(int id, int p_id, datetime start) I want to generate a view that gives me PS(S.id, P.id, S.start + P.minutes) by joining S.p_id=P.id The problem is, if I was generating the query from the application, I can do stuff like: select datetime('2010-04-21 14:00', '+20 minutes'); 2010-04-21 14:20:00 By creating the string '+20 minutes' in the application and then passing it to sqlite. However I can't find a way to create this string in the select itself: select p.*,datetime(s.start_at, formatstring('+%s minutes', p.minutes)) from p,s where s.p_id=p.id; Because sqlite as far the documentation tells, does not provide any string format function, nor can I see any alternative way of expressing the date modifiers.

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  • MySQL Query, how to group and count in one row ?

    - by Akarun
    Hi All, To simplify, I have tree tables: products, products-vs-orders, orders products fields : 'ProductID', 'Name', 'isGratis', ... products-vs-orders fields : 'ProductID', 'OrderID' orders fields : 'OrderID', 'Title', ... Actually, I have a query like this: SELECT orders.OrderID, orders.Title, COUNT(`products`.`isGratis`) AS "Quantity", `products`.`isGratis` FROM `orders`, `products-vs-orders`, `products` WHERE `orders`.`OrderID` = `products-vs-orders`.`OrderID` AND `products-vs-orders`.`ProductID` = `products`.`ProductID` GROUP BY `products`.`PackID`, `products`.`isGratis` This query works and return this surch of result: OrderID, Title, Quantity, isGratis 1 My Order 20 0 1 My Order 3 1 2 An other 8 0 2 An other 1 1 How can I retrieve the count of products 'gratis' and 'paid' in to separate cols ? OrderID, Title, Qt Paid, Qt Gratis 1 My Order 20 3 2 An other 8 1 Thanks for your help

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  • Converting time/date from XML file into MYSQL format

    - by IconicDigital
    One of the affiliate networks provides a feed with the following time/date format. <startDate>1349992800000</startDate> <endDate>1355266799999</endDate> My problem is I am trying to convert this to a MYSQL format, I have tried mktime and strtotime with no luck the date seems to come out wrong. I know this is the time since the Equinox, I am just not sure how to convert this to a MYSQL format.

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  • CakePHP repeats same queries

    - by Rytis
    I have a model structure: Category hasMany Product hasMany Stockitem belongsTo Warehouse, Manufacturer. I fetch data with this code, using containable to be able to filter deeper in the associated models: $this->Category->find('all', array( 'conditions' => array('Category.id' => $category_id), 'contain' => array( 'Product' => array( 'Stockitem' => array( 'conditions' => array('Stockitem.warehouse_id' => $warehouse_id), 'Warehouse', 'Manufacturer', ) ) ), ) ); Data structure is returned just fine, however, I get multiple repeating queries like, sometimes hundreds of such queries in a row, based on dataset. SELECT `Warehouse`.`id`, `Warehouse`.`title` FROM `beta_warehouses` AS `Warehouse` WHERE `Warehouse`.`id` = 2 Basically, when building data structure Cake is fetching data from mysql over and over again, for each row. We have datasets of several thousand rows, and I have a feeling that it's going to impact performance. Is it possible to make it cache results and not repeat same queries?

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  • A case-insensitive related implementation problem

    - by Robert
    Hi All, I am going through a final refinement posted by the client, which needs me to do a case-insesitive query. I will basically walk through how this simple program works. First of all, in my Java class, I did a fairly simple webpage parsing: title=(String)results.get("title"); doc = docBuilder.parse("http://" + server + ":" + port + "/exist/rest/db/wb/xql/media_lookup.xql?" + "&title=" + title); This Java statement references an XQuery file "media_lookup.xql" which is stored on localhost, and the only parameter we are passing is the string "title". Secondly, let's take at look at that XQuery file: $title := request:get-parameter('title',""), $mediaNodes := doc('/db/wb/portfolio/media_data.xml'), $query := $mediaNodes//media[contains(title,$title)], Then it will evaluate that query. This XQuery will get the "title" parameter that are passes from our Java class, and query the "media_data" xml file stored in the database, which contains a bunch of media nodes with a 'title' element node. As you may expect, this simple query will just match those media nodes whose 'title' element contains a substring of what the value of string 'title' is. So if our 'title' is "Chi", it will return media nodes whose title may be "Chicago" or "Chicken". The refinment request posted by the client is that there should be NO case-sensitivity. The very intuitive way is to modify the XQuery statement by using a lower-case funtion in it, like: $query := $mediaNodes//media[contains(lower-case(title/text(),lower-case($title))], However, the question comes: this modified query will run my machine into memory overflow. Since my "media_data.xml" is quite huge and contains thouands of millions of media nodes, I assume the lower-case() function will run on each of the entries, thus causing the machine to crash. I've talked with some experienced XQuery programmer, and they think I should use an index to solve this problem, and I will definitely research into that. But before that, I am just posting this problem here to get other ideas or any suggestions, do you think any other way may help? for example, could I tweak the Java parse statement to realize the case-insensitivity? Since I think I saw some people did some string concatination by using "contains." in Java before passing it to the server. Any idea or help is welcomed, thanks in advance.

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  • mysql replace matching but not changing

    - by alex
    I've used mysql's update replace function before, but even though I think I'm following the same syntax, I can't get this to work-it matches the rows, but doesn't replace. Here's what I'm trying to do: mysql> update contained_widgets set preference_values = replace(preference_values, '<li><a_href="/enewsletter"><span class="not-tc">eNewsletter</span></a></li>', '<li><a_href="/enewsletter"><span class="not-tc">eNewsletter</span></a></li> <li> <a_href="/projects"><span class="not-tc">Projects</span></a></li>'); Query OK, 0 rows affected (0.00 sec) Rows matched: 77 Changed: 0 Warnings: 0 I don't see what I'm missing. Any help is appreciated. I edited "a " to "a_" because the site thinks I'm posting spam links otherwise.

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  • Choosing between a union and a boolean condition

    - by bread
    Does this require a UNION? SELECT vend_id, prod_id, prod_price FROM products WHERE prod_price <= 5 UNION SELECT vend_id, prod_id, prod_price FROM products WHERE vend_id IN (1001,1002); Or is it the same if you do it this way? SELECT vend_id, prod_id, prod_price FROM products WHERE prod_price <= 5 OR vend_id IN (1001,1002);

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  • Union All Won't work in stored procedure

    - by MyHeadHurts
    ALTER PROCEDURE [dbo].[MyStoredProcedure1] @YearToGet int AS Select Division, SDESCR, DYYYY, Sum(APRICE) ASofSales, Sum(PARTY) AS ASofPAX, Sum(NetAmount) ASofNetSales, Sum(InsAmount) ASofInsSales, Sum(CancelRevenue) ASofCXSales, Sum(OtherAmount) ASofOtherSales, Sum(CXVALUE) ASofCXValue From dbo.B101BookingsDetails Where Booked <= CONVERT(int,DateAdd(year, @YearToGet - Year(getdate()), DateAdd(day, DateDiff(day, 1, getdate()), 0) ) ) and (DYYYY = @YearToGet) Group By SDESCR, DYYYY, Division Having (DYYYY = @YearToGet) Order By Division, SDESCR, DYYYY union all SELECT DIVISION, SDESCR, DYYYY, SUM(APRICE) AS YESales, SUM(PARTY) AS YEPAX, SUM(NetAmount) AS YENetSales, SUM(InsAmount) AS YEInsSales, SUM(CancelRevenue) AS YECXSales, SUM(OtherAmount) AS YEOtherSales, SUM(CXVALUE) AS YECXValue FROM dbo.B101BookingsDetails Where (DYYYY=@YearToGet) GROUP BY SDESCR, DYYYY, DIVISION ORDER BY DIVISION, SDESCR, DYYYY The error I am getting is Msg 156, Level 15, State 1, Procedure MyStoredProcedure1, Line 36 Incorrect syntax near the keyword 'union'. But my goal here is the user inputs a year for example 2009, my first query will get all the sales made in 2009 to the same date it is was yesterday 12/23/2009, while the second query is getting 2009 totals up to dec 31 2009. I want the columns to be side by side not in one column

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  • What does DataContext.GetTable<TEntry> do?

    - by Bryan
    Consider I have a DataContext db, and there is an Entity class User. So when System.Data.Linq.Table<User> table = db.GetTable<User>(); is called for the first time, does it pull the data from the database immediately, does it use deferred execution, or were the data already loaded from database when db was initialized?

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  • sql data source

    - by George
    I have a table (EmployeeID,EmployeeName,ManagerID) How can I create a sqldatasource to include the ManagerName from the EmployeeName given EmployeeID = ManagerID? In my gridview after dragging a dropdownlist what bindings should I do to display the managerName? Is it possible to use it without writing custom select,insert,delete,update? If not what are the steps I need to do to write the whole thing i.e. custom grid and source? Thank you very much

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  • Calculate open timeslots given availability and existing appointments - by day

    - by Andre
    Overview: I have a table which stores a persons "availability" for a current day, e.g. Mon - 8:00am - 11:30am Mon - 1:30pm - 6:00pm A second table stores appointments that this person already has for the same day, e.g. Mon - 8:30am - 11:00am Mon - 2:30pm - 4pm Desired result: Doing calculationsI'd like to have the following result - e.g. "this person has availability on the given day": Mon - 8:00am - 8:30am Mon - 11:00am - 11:30am Mon - 1:30pm - 2:30pm Mon - 4:00pm - 6:00pm Any ideas on how to calculate the output given the two inputs (e.g. availability, existing appointments) would be greatly appreciated. Preferably I'd use javascript on the client to do the calculating as I would believe that doing it within the DB (I'm using MSSQL) would be slow for many records, persons, etc. Hope this is enough information to illustrate the problem at hand - Many thanks in advance.

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  • filter by multiple attributes

    - by cosy
    I have the table : id id_products id_atribut name value 1 13 8 autdio 2.1 2 13 9 hdd 200 Gb 3 13 10 cd-rom 2 4 20 8 audio 2.1 the problem is, how can i select from this table where name="audio" and value="2.1" and name="hdd" and value="200 gb" and return id_products=13 .... How can i do this?

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  • Creating a Doctrine query with a different number of ids

    - by frapet
    Is it possible to create a Doctrine query with a differnt number of ids coming from a submitted form? And if yes how? What I am trying to do is this: .... if ($input->isValid()) { $q = Doctrine_Query::create() ->from('Imm_Model_Images i') ->whereIn('i.ImageID = ?', array($input->ids)); $result = $q->fetchArray(); PS: ids come form the submitted form in an array as ids[]. Added Edit: chaged the above line: ->whereIn('i.ImageID = ?', array($input->ids)); with: ->whereIn('i.ImageID = array($input->ids)'); ...and it seems to work.

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  • Oracle: What does `(+)` do in a WHERE clause?

    - by Jonathan Lonowski
    Found the following in an Oracle-based application that we're migrating (generalized): SELECT Table1.Category1, Table1.Category2, count(*) as Total, count(Tab2.Stat) AS Stat FROM Table1, Table2 WHERE (Table1.PrimaryKey = Table2.ForeignKey(+)) GROUP BY Table1.Category1, Table1.Category2 What does (+) do in a WHERE clause? I've never seen it used like that before.

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