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  • Database: storing data from user registration form

    - by teggy
    Let's say I have an user registration form. In this form, I have the option for the user to upload a photo. I have an User table and Photo table. My User table has a "PathToPhoto" column. My question is how do I fill in the "PathToPhoto" column if the photo is uploaded and inserted into Photo table before the user is created? Another way to phrase my question is how to get the newly uploaded photo to be associated to the user that may or may not be created next. I'm using python and postgresql.

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  • Practical rules for premature optimization

    - by DougW
    It seems that the phrase "Premature Optimization" is the buzz-word of the day. For some reason, iphone programmers in particular seem to think of avoiding premature optimization as a pro-active goal, rather than the natural result of simply avoiding distraction. The problem is, the term is beginning to be applied more and more to cases that are completely inappropriate. For example, I've seen a growing number of people say not to worry about the complexity of an algorithm, because that's premature optimization (eg http://stackoverflow.com/questions/2190275/help-sorting-an-nsarray-across-two-properties-with-nssortdescriptor/2191720#2191720). Frankly, I think this is just laziness, and appalling to disciplined computer science. But it has occurred to me that maybe considering the complexity and performance of algorithms is going the way of assembly loop unrolling, and other optimization techniques that are now considered unnecessary. What do you think? Are we at the point now where deciding between an O(n^n) and O(n!) complexity algorithm is irrelevant? What about O(n) vs O(n*n)? What do you consider "premature optimization"? What practical rules do you use to consciously or unconsciously avoid it? This is a bit vague, but I'm curious to hear other peoples' opinions on the topic.

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  • Database Modeling - Either/Or in Many-to-Many

    - by EkoostikMartin
    I have an either/or type of situation in a many-to-many relationship I'm trying to model. So I have these tables: Message ---- *MessageID MessageText Employee ---- *EmployeeID EmployeeName Team ---- *TeamID TeamName MessageTarget ---- MessageID EmployeeID (nullable) TeamID (nullable) So, a Message can have either a list of Employees, or a list of Teams as a MessageTarget. Is the MessageTarget table I have above the best way to implement this relationship? What constraints can I place on the MessageTarget effectively? How should I create a primary key on MessageTarget table?

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  • add Constraint on database with trigger

    - by Am1rr3zA
    Hi, I have 3 tables (Student, Course, student_course_choose(have field grade)) I defined a view on these 3 tables that get me an Average of the each student. I want to have constraint(with trigger) on these view(or on the table that need it) to limit the average of each student between 13 and 18. I somewhere read that I must use foreach statement(instead of foreach row) on trigger because when I decrease some grade of special student and his/her average become less than 13 they don't give me error (because later I increase grade of another his/her course ). how must I wrote this Trigger? (I want to implement aprh for testing trigger) note:I can write it in SQL server, oracle or Mysql no diff for me.

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  • I can't create a view in oracle database using sqlplus (insufficient privileges)

    - by Nubkadiya
    I'm running this SQL: CREATE VIEW showMembersInfo(MemberID,Fname,Lname,Address,DOB,Telephone,NIC,Email,WorkplaceID,WorkName,WorkAddress,WorkTelephone,StartingDate,ExpiryDate,Amount,WitnessID,WitName,WitAddress,WitNIC,WitEmail,WitTelephone) AS SELECT mem.MemberID,mem.FirstName,mem.LastName,mem.Address,mem.DOB,mem.Telephone,mem.NIC,mem.Email, wrk.WorkPlaceID,wrk.Name,wrk.Address,wrk.Telephone, anl.StartingDate,anl.ExpiryDate,anl.Amount, wit.WitnessID,wit.Name,wit.Address,wit.NIC,wit.Email,wit.Telephone FROM Member mem, WorkPlace wrk, AnnualFees anl, Witness wit WHERE mem.MemberID = anl.MemberID AND mem.WorkPlaceID = work.WorkPlaceID AND mem.WitnessID = wit.WitnessID When I try to create the view I get this error: ERROR at line 1: ORA-01031: insufficient privileges Why is that? I'm logged in to sqlplus using sysman

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  • SQL Server database change workflow best practices

    - by kubi
    The Background My group has 4 SQL Server Databases: Production UAT Test Dev I work in the Dev environment. When the time comes to promote the objects I've been working on (tables, views, functions, stored procs) I make a request of my manager, who promotes to Test. After testing, she submits a request to an Admin who promotes to UAT. After successful user testing, the same Admin promotes to Production. The Problem The entire process is awkward for a few reasons. Each person must manually track their changes. If I update, add, remove any objects I need to track them so that my promotion request contains everything I've done. In theory, if I miss something testing or UAT should catch it, but this isn't certain and it's a waste of the tester's time, anyway. Lots of changes I make are iterative and done in a GUI, which means there's no record of what changes I made, only the end result (at least as far as I know). We're in the fairly early stages of building out a data mart, so the majority of the changes made, at least count-wise, are minor things: changing the data type for a column, altering the names of tables as we crystallize what they'll be used for, tweaking functions and stored procs, etc. The Question People have been doing this kind of work for decades, so I imagine there have got to be a much better way to manage the process. What I would love is if I could run a diff between two databases to see how the structure was different, use that diff to generate a change script, use that change script as my promotion request. Is this possible? If not, are there any other ways to organize this process? For the record, we're a 100% Microsoft shop, just now updating everything to SQL Server 2008, so any tools available in that package would be fair game.

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  • HTML5 Database Transactions

    - by jiewmeng
    i am wondering abt the example W3C Offline Web Apps the example function renderNotes() { db.transaction(function(tx) { tx.executeSql('CREATE TABLE IF NOT EXISTS Notes(title TEXT, body TEXT)', []); tx.executeSql(‘SELECT * FROM Notes’, [], function(tx, rs) { for(var i = 0; i < rs.rows.length; i++) { renderNote(rs.rows[i]); } }); }); } has the create table before the 'main' executeSql(). will it be better if i do something like $(function() { // create table 1st db.transaction(function(tx) { tx.executeSql('CREATE TABLE IF NOT EXISTS Notes(title TEXT, body TEXT)', []); }); // when i execute say to select/modify data, i just do the actual action db.transaction(function(tx) { tx.executeSql(‘SELECT * FROM Notes’, [], function(tx, rs) { ... } }); db.transaction(function(tx) { tx.executeSql(‘INSERT ...’, [], function(tx, rs) { ... } }); }) i was thinking i don't need to keep repeating the CREATE IF NOT EXISTS right?

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  • Advantage Database Server ORDER BY behaviour

    - by ie
    I'm using ADS v10 beta. I'm trying to numerate ordered resultset. 1) ORDER BY in nested queries. I need to use nested SELECT for some calculations: SELECT Name, Value, ROWNUM() FROM (SELECT * FROM MainTable WHERE Value > 0 ORDER BY Value) a And I'm getting Expected lexical element not found: ) There was a problem parsing the table names after the FROM keyword in your SELECT statement. Everything is working well when the ORDER BY is removed. Although, I found the sample in the Help, it looks like my query (more complex, indeed): SELECT * FROM (SELECT TOP 10 empid, fullname FROM branch1 ORDER BY empid) a UNION SELECT empid, fullname FROM branch2 ORDER BY empid 2) ORDER BY + ROWNUM(). I used the nested query in the example above, to numerate ordered rows. Is there are any chance to avoid nested query? In the SQL Server I can do something like this: SELECT Name, Value, ROW_NUMBER() OVER(ORDER BY Value) FROM MainTable WHERE Value > 1 ORDER BY Value Please advice. Thanks.

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  • Oracle Database introduction and literature

    - by Marco Nätlitz
    Hi folks, got an new assignment covering Oracle databases. My problem now is that I am completely new to the Oracle system and never worked with it before. I need to develop a concept covering the installation and configuration of the server. Afterwards I need to migrate the old server to the new while ensuring date consistence. I just wanted to ask if you guys have some useful links for introduction and of course good literature / books on this topic? Thanks and cheers from Cologne Marco

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  • Storing year/make/model in a database?

    - by Mark
    Here's what I'm thinking (excuse the Django format): class VehicleMake(Model): name = CharField(max_length=50) class VehicleModel(Model): make = ForeignKey(VehicleMake) name = CharField(max_length=50) class VehicleYear(Model): model = ForeignKey(VehicleModel) year = PositiveIntegerField() This is going to be used in those contingent drop-down select boxes, which would visually be laid out like [- Year -][- Make -][- Model -]. So, to query the data I need I would first have to select all distinct years from the years table, sorted descending. Then I'd find all the vehicle makes that have produced a model in that year. And then all the models by that make in that year. Is this a good way to do it, or should I re-arrange the foreign keys somehow? Or use a many-to-many table for the years/models so that no year is repeated?

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  • Rails - authoritative source for your database schema?

    - by keruilin
    I have Rails app, and every once in a while, when I bring new developer onboard they exclaim that they should be able to produce the current DB schema in their dev environment by running the whole history of the migrations. I personally don't think that migrations is the authoritative source for your schema. Right now what we do is load a production copy of the DB, with the current schema, onto the dev machine. And, from there, the schema can be maintained via incremental migrations. So my question are: What is the authoritative source of your schema on a Rails project? What is now considered the best-practice way to maintain your DB schema?

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  • Hibernate database integrity with multiple java applications

    - by Austen
    We have 2 java web apps both are read/write and 3 standalone java read/write applications (one loads questions via email, one processes an xml feed, one sends email to subscribers) all use hibernate and share a common code base. The problem we have recently come across is that questions loaded via email sometimes overwrite questions created in one of the web apps. We originally thought this to be a caching issue. We've tried turning off the second level cache, but this doesn't make a difference. We are not explicitly opening and closing sessions, but rather let hibernate manage them via Util.getSessionFactory().getCurrentSession(), which thinking about it, may actually be the issue. We'd rather not setup a clustered 2nd level cache at this stage as this creates another layer of complexity and we're more than happy with the level of performance we get from the app as a whole. So does implementing a open-session-in-view pattern in the web apps and manually managing the sessions in the standalone apps sound like it would fix this? Or any other suggestions/ideas please? <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property> <property name="hibernate.current_session_context_class">thread</property> <property name="hibernate.cache.use_second_level_cache">false</property>

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  • Database layout tagging system

    - by Kurresmack
    I am creating a web site for a customer and they want to be able to create articles. My idea is to tag them so I am going to implement the system. What is the best design, both from an architectural and a perfomance perspective: 1. To have table with all tags and then have a one to many relationship table that links a tag like this: articles table with ID tags table with ID one to many table with columns Article.ID and Tags.ID 2. To have one table with articles and one with tags for articles like this: articles table with ID tags table with Article.ID and tag text Thanks in advance!

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  • Auto complete from database using CodeIgniter (Active Record)

    - by Ralph David Abernathy
    I have a form on my website in which one is able to submit a cat. The form contains inputs such as "Name" and "Gender", but I am just trying to get the auto completion to work with the "Name" field. Here is what my jquery looks like : $(document).ready(function() { $( "#tags" ).autocomplete({ source: '/Anish/auto_cat' }); }); Here is what my model looks like: public function auto_cat($search_term) { $this->db->like('name', $search_term); $response = $this->db->get('anish_cats')->result_array(); // var_dump($response);die; return $response; } } Here is my controller: public function auto_cat(){ $search_term = $this->input->get('term'); $cats = $this->Anish_m->auto_cat($search_term); } And here is my view: <head> <link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css" /> <script src="http://code.jquery.com/jquery-1.9.1.js"></script> <script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script> <link rel="stylesheet" href="/resources/demos/style.css" /> </head> <h1>Anish's Page</h1> <form action="/Anish/create" method="POST"> <div class="ui-widget"> <label for="tags">Name</label><input id="tags" type="text" name="name"> </div> <div> <label>Age</label><input type="text" name="age"> </div> <div> <label>Gender</label><input type="text" name="gender"> </div> <div> <label>Species</label><input type="text" name="species"> </div> <div> <label>Eye Color</label><input type="text" name="eye_color"> </div> <div> <label>Color</label><input type="text" name="color"> </div> <div> <label>Description</label><input type="text" name="description"> </div> <div> <label>marital status</label><input type="text" name="marital_status"> </div> <br> <button type="submit" class="btn btn-block btn-primary span1">Add cat</button> </form> <br/><br/><br/><br/> <table class="table table-striped table-bordered table-hover"> <thead> <tr> <th>Name</th> <th>Gender</th> <th>Age</th> <th>Species</th> <th>Eye Color</th> <th>Color</th> <th>Description</th> <th>Marital Status</th> <th>Edit</th> <th>Delete</th> </tr> </thead> <tbody> <?php foreach ($cats as $cat):?> <tr> <td> <?php echo ($cat['name']);?><br/> </td> <td> <?php echo ($cat['gender']);?><br/> </td> <td> <?php echo ($cat['age']);?><br/> </td> <td> <?php echo ($cat['species']);?><br/> </td> <td> <?php echo ($cat['eye_color']);?><br/> </td> <td> <?php echo ($cat['color']);?><br/> </td> <td> <?php echo ($cat['description']);?><br/> </td> <td> <?php echo ($cat['marital_status']);?><br/> </td> <td> <form action="/Anish/edit" method="post"> <input type="hidden" value="<?php echo ($cat['id']);?>" name="Anish_id_edit"> <button class="btn btn-block btn-info">Edit</button> </form> </td> <td> <form action="/Anish/delete" method="post"> <input type="hidden" value="<?php echo ($cat['id']);?>" name="Anish_id"> <button class="btn btn-block btn-danger">Delete</button> </form> </td> </tr> <?php endforeach;?> </tbody> </table> I am stuck. In my console, I am able to see this output when I type the letter 'a' if I uncomment the var_dump in my model: array(4) { [0]=> array(9) { ["id"]=> string(2) "13" ["name"]=> string(5) "Anish" ["gender"]=> string(4) "Male" ["age"]=> string(2) "20" ["species"]=> string(3) "Cat" ["eye_color"]=> string(5) "Brown" ["color"]=> string(5) "Black" ["description"]=> string(7) "Awesome" ["marital_status"]=> string(1) "0" } [1]=> array(9) { ["id"]=> string(2) "16" ["name"]=> string(5) "Anish" ["gender"]=> string(2) "fe" ["age"]=> string(2) "23" ["species"]=> string(2) "fe" ["eye_color"]=> string(2) "fe" ["color"]=> string(2) "fe" ["description"]=> string(2) "fe" ["marital_status"]=> string(1) "1" } [2]=> array(9) { ["id"]=> string(2) "17" ["name"]=> string(1) "a" ["gender"]=> string(1) "a" ["age"]=> string(1) "4" ["species"]=> string(1) "a" ["eye_color"]=> string(1) "a" ["color"]=> string(1) "a" ["description"]=> string(1) "a" ["marital_status"]=> string(1) "0" } [3]=> array(9) { ["id"]=> string(2) "18" ["name"]=> string(4) "Matt" ["gender"]=> string(6) "Female" ["age"]=> string(2) "80" ["species"]=> string(6) "ferret" ["eye_color"]=> string(4) "blue" ["color"]=> string(4) "pink" ["description"]=> string(5) "Chill" ["marital_status"]=> string(1) "0" } }

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  • Rails: Auto-Detecting Database Adapter

    - by Dex
    The new version of the ar-extensions gem requires that you load the appropriate adapter yourself. On my development side I use mysql, however Heroku uses PostgreSQL. For example, on my development side I need to do this: require 'ar-extensions/adapters/mysql' require 'ar-extensions/import/mysql' How can I audo-detect which adapter to use?

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  • How to implement Auto_Increment per User, on the same table?

    - by Jonas
    I would like to have multiple users that share the same tables in the database, but have one auto_increment value per user. I will use an embedded database, JavaDB and as what I know it doesn't support this functionality. How can I implement it? Should I implement a trigger on inserts that lookup the users last inserted row, and then add one, or are there any better alternative? Or is it better to implement this in the application code? Or is this just a bad idea? I think this is easier to maintain than creating new tables for every user. Example: table +----+-------------+---------+------+ | ID | ID_PER_USER | USER_ID | DATA | +----+-------------+---------+------+ | 1 | 1 | 2 | 3454 | | 2 | 2 | 2 | 6567 | | 3 | 1 | 3 | 6788 | | 4 | 3 | 2 | 1133 | | 5 | 4 | 2 | 4534 | | 6 | 2 | 3 | 4366 | | 7 | 3 | 3 | 7887 | +----+-------------+---------+------+ SELECT * FROM table WHERE USER_ID = 3 +----+-------------+---------+------+ | ID | ID_PER_USER | USER_ID | DATA | +----+-------------+---------+------+ | 3 | 1 | 3 | 6788 | | 6 | 2 | 3 | 4366 | | 7 | 3 | 3 | 7887 | +----+-------------+---------+------+ SELECT * FROM table WHERE USER_ID = 2 +----+-------------+---------+------+ | ID | ID_PER_USER | USER_ID | DATA | +----+-------------+---------+------+ | 1 | 1 | 2 | 3454 | | 2 | 2 | 2 | 6567 | | 4 | 3 | 2 | 1133 | | 5 | 4 | 2 | 4534 | +----+-------------+---------+------+

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  • database structure

    - by jindalsyogesh
    I have a table named ActivityRecording. This table currently has 500,000 records. I need to add a lot of new inputs that relates to activityrecording table. The relation of activityrecording with these new input fields is 1 to 0,1. So, what's going to happen on screen is when user fills the ActivityRecording data, he will then be taken to a new page and this page will show a form based on the user's input (from a dropdown named service) in activityrecording. There will 6 different kinds of form (each form will have 7-8 inputs which includes textareas of size 5kb, textboxes and checkboxes). So, for one activityrecording user will fill one out of 6 forms. There are two ways I know (there could be more), I can design the data structure: Add all the inputs from all these 6 forms into the activityrecording table. So, columns belonging to 5 of these forms will be null in this table, only columns belonging to one of the forms will have values The other way would be add 6 new tables (one for each form) and add 6 foreign key columns to activityrecording table. So, out of 6 foreign keys, 5 will be null and one will actually point to a table Which approach is a better data structure design? Please take into consideration that number of rows in this table are 500,000 and are expected to grow at a faster rate now.

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  • php java in memory database

    - by msaif
    i need to load data as array to memory in PHP.but in PHP if i write $array= array("1","2"); in test.php then this $array variable is initialized every time user requests.if we request test.php 100 times by clicking 100 times browser refresh button then this $array variable will be executed 100 times. but i need to execute the $array variable only one time for first time request and subsequent request of test.php must not execute the $array variable.but only use that memory location.how can i do that in PHP. but in JAVA SEVRVLET it is easy to execute,just write the $array variable in one time execution of init() method of servlet lifecycle method and subsequent request of that servlet dont execute init() method but service() method but service() method always uses that $array memeory location. all i want to initilize $array variable once but use that memory loc from subsequent request in PHP.is there any possiblity in PHP?

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  • How to virtually delete data from multiple tables that are linked by a foreign key ?

    - by Shantanu Gupta
    I am using Sql Server 2005 This is a part of my database diagram. I want to perform deletion on my database which will start from tblDomain up tp tblSubTopics. Consider that each table has IsDeleted column which has to be marked true if request was made to delete data. But that data shoud remain their physically. Tables which will have IsDeleted Column are tblDomain tblSubject tblTopic tblSubTopic Now I want, if a user marks one domain as deleted then all the refrence field should also get marked as deleted. i.e. 1 domain is related to 5 subjects, those 5 subjects are related to 25 topics, those 25 topics are related to 500 subtopics and so on. Then how should i mark all these fileds as Deleted. ?

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  • Database storage for high sample rate data in web app

    - by Jim
    I've got multiple sensors feeding data to my web app. Each channel is 5 samples per second and the data gets uploaded bundled together in 1 minute json messages (containing 300 samples). The data will be graphed using flot at multiple zoom levels from 1 day to 1 minute. I'm using Amazon SimpleDB and I'm currently storing the data in the 1 minute chunks that I receive it in. This works well for high zoom levels, but for full days there will be simply be too many rows to retrieve. The idea I've currently got is that every hour I can crawl through the data and collect together 300 samples for the last hour and store them in an hour Domain (table if you like). Does this sound like a reasonable solution? How have others implemented the same sort of systems?

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