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  • How to map combinations of things to a relational database?

    - by Space_C0wb0y
    I have a table whose records represent certain objects. For the sake of simplicity I am going to assume that the table only has one row, and that is the unique ObjectId. Now I need a way to store combinations of objects from that table. The combinations have to be unique, but can be of arbitrary length. For example, if I have the ObjectIds 1,2,3,4 I want to store the following combinations: {1,2}, {1,3,4}, {2,4}, {1,2,3,4} The ordering is not necessary. My current implementation is to have a table Combinations that maps ObjectIds to CombinationIds. So every combination receives a unique Id: ObjectId | CombinationId ------------------------ 1 | 1 2 | 1 1 | 2 3 | 2 4 | 2 This is the mapping for the first two combinations of the example above. The problem is, that the query for finding the CombinationId of a specific Combination seems to be very complex. The two main usage scenarios for this table will be to iterate over all combinations, and the retrieve a specific combination. The table will be created once and never be updated. I am using SQLite through JDBC. Is there any simpler way or a best practice to implement such a mapping?

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  • How to quickly save more than a thousand entries in the database in NHibernate?

    - by Anry
    I create and retain objects of business class in the loop for (int i = num.StartNumber; i <= num.EndNumber; i++) { var voucher = new Domain.GiftVouchers { UniqueNumber = i.ToString(), Denomination = num.Denomination, ExpiryDateTime = DateTime.Now }; voucher.Save(); } The method of preservation NHibernate using (ISession session = NHibernateHelper.OpenSession()) using (ITransaction transaction = session.BeginTransaction()) { session.SaveOrUpdate(giftVouchers); transaction.Commit(); } If you generate 1000 + entries, we have to wait long. How can I increase the speed of this operation?

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  • Zip Code to City/State and vice-versa in a database?

    - by Simucal
    I'm new to SQL and relational databases and I have what I would imagine is a common problem. I'm making a website and when each user submits a post they have to provide a location in either a zip code or a City/State. What is the best practice for handling this? Do I simply create a Zip Code and City and State table and query against them or are there ready made solutions for handling this? I'm using SQL Server 2005 if it makes a difference. I need to be able to retrieve a zip code given a city/state or I need to be able to spit out the city state given a zip code.

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  • My Linq to Sql Insert code seems to work fine but I don't get a record in the database

    - by Alex
    Here is my code. In the debugger, I can see that the code is running. No errors are thrown. But, when I go back to the table, no row has been inserted. What am I missing?? protected void submitButton_Click(object sender, EventArgs e) { CfdDataClassesDataContext db = new CfdDataClassesDataContext(); string sOfficeSought = officesSoughtDropDownList.SelectedValue; int iOfficeSought; Int32.TryParse(sOfficeSought, out iOfficeSought); Account act = new Account() { FirstName = firstNameTextBox.Text, MiddleName = middleNamelTextBox.Text, LastName = lastNameTextBox.Text, Suffix = suffixTextBox.Text, CampaignName = campaignNameTextBox.Text, Address1 = address1TextBox.Text, Address2 = address2TextBox.Text, TownCity = townCityTextBox.Text, State = stateTextBox.Text, ZipCode = zipTextBox.Text, Phone = phoneTextBox.Text, Fax = faxTextBox.Text, PartyAffiliation = partyAfilliatinoTextBox.Text, EmailAddress = emailTextBox.Text, BankName = bankNameTextBox.Text, BankMailingAddress = bankAddressTextBox.Text, BankTownCity = bankTownCityTextBox.Text, BankState = bankStateTextBox.Text, BankZip = bankZipTextBox.Text, TreasurerFirstName = treasurerFirstNameTextBox.Text, TreasurerMiddleName = treasurerMiddleNamelTextBox.Text, TreasurerLastName = treasurerLastNameTextBox.Text, TreasurerMailingAddress = treasurerMailingAddressTextBox.Text, TreasurerTownCity = treasurerTownCityTextBox.Text, TreasurerState = treasurerStateTextBox.Text, TreasurerZipCode = treasurerZipTextBox.Text, TreasurerPhone = treasurerPhoneTextBox.Text //OfficeSought = iOfficeSought }; act.Suffix = suffixTextBox.Text; db.SubmitChanges(); }

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  • Can in-memory SQLite databases scale with concurrency?

    - by Kent Boogaart
    In order to prevent a SQLite in-memory database from being cleaned up, one must use the same connection to access the database. However, using the same connection causes SQLite to synchronize access to the database. Thus, if I have many threads performing reads against an in-memory database, it is slower on a multi-core machine than the exact same code running against a file-backed database. Is there any way to get the best of both worlds? That is, an in-memory database that permits multiple, concurrent calls to the database?

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  • Can in-memory SQLite databases be used concurrently?

    - by Kent Boogaart
    In order to prevent a SQLite in-memory database from being cleaned up, one must use the same connection to access the database. However, using the same connection causes SQLite to synchronize access to the database. Thus, if I have many threads performing reads against an in-memory database, it is slower on a multi-core machine than the exact same code running against a file-backed database. Is there any way to get the best of both worlds? That is, an in-memory database that permits multiple, concurrent calls to the database?

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  • Do you know good software for a knowledge database ?

    - by Eric
    Hello, I am looking for a professional software (not free) for knowledge management with a web interface. Something where one can search technical documentations ( Bugs, Patches, Solutions, White Papers, Documentation and Support Knowledge ) and where documents can be moderated.

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  • How to handle when SSRS does not automatically update fields based on database query?

    - by badpanda
    So I am trying to change the number of fields in my dataset in SSRS and the refresh button is not picking up the added field from the SQL server. The query is definitely returning the correct data, as I have double checked in the server engine itself. Also, I have tried manually adding the field using the SSRS menu, but as soon as I execute it disappears. Any suggestions or similar experiences?

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  • Using IPrinciple.Identity.Name as a key in a dataBase to identify user's rows.

    - by bplus
    I'm writing a small intranet app that uses Windows Authentication and Asp.Net MVC. I need to store various bits of data in a db against each user. As far as I can tell the IPrinciple object does not seem to have something like a unique id. So I was thinking I could just use User.Identity.Name as a unique value to identify rows in my db. Is this a bad idea? Is there an alternative to this approach? Thanks for any help.

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  • How to feed an xml database with tags obtained thru html forms ?

    - by blaise1
    Hello! Not a programmer, I begin with xml, html forms and xslt on Mac. I plan to use a form to post short texts in a xhtml page and invite end users to add some annotations to the said text. The users would select a specific part of the text posted and each annotation would stand for one specific chain of characters. My goal is to consolidate the tags obtained from various user's annotations to one xml "knowledge base" containing the original text with all the revision indicators. Then I plan to use xslt sheets to product various reports based on the tags obtained. my two questions are : 1- am I dreaming ? Is it really possible to do that with xml, xforms, xslt without using java, php, ajax or other seasoned programmer's tools ? 2- What should be my focus for further explorations aiming in that direction ? Which schema, events, sequences should I study ? Je vous remercie à l'avance, Please excuse my English. Blaise

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  • Multiple calculations on the same set of data: ruby or database?

    - by Pierre
    Hi, I have a model Transaction for which I need to display the results of many calculations on many fields for a subset of transactions. I've seen 2 ways to do it, but am not sure which is the best. I'm after the one that will have the least impact in terms of performance when data set grows and number of concurrent users increases. data[:total_before] = Transaction.where(xxx).sum(:amount_before) data[:total_after] = Transaction.where(xxx).sum(:amount_after) ... or transactions = Transaction.where(xxx) data[:total_before]= transactions.inject(0) {|s, e| s + e.amount_before } data[:total_after]= transactions.inject(0) {|s, e| s + e.amount_after } ... Which one should I choose? (or is there a 3rd, better way?) Thanks, P.

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  • How do I go about link web content in a database with a nested set model?

    - by wb
    My nested set table is as follows. create table depts ( id int identity(0, 1) primary key , lft int , rgt int , name nvarchar(60) , abbrv nvarchar(20) ); Test departments. insert into depts (lft, rgt, name, abbrv) values (1, 14, 'root', 'r'); insert into depts (lft, rgt, name, abbrv) values (2, 3, 'department 1', 'd1'); insert into depts (lft, rgt, name, abbrv) values (4, 5, 'department 2', 'd2'); insert into depts (lft, rgt, name, abbrv) values (6, 13, 'department 3', 'd3'); insert into depts (lft, rgt, name, abbrv) values (7, 8, 'sub department 3.1', 'd3.1'); insert into depts (lft, rgt, name, abbrv) values (9, 12, 'sub department 3.2', 'd3.2'); insert into depts (lft, rgt, name, abbrv) values (10, 11, 'sub sub department 3.2.1', 'd3.2.1'); My web content table is as follows. create table content ( id int identity(0, 1) , dept_id int , page_name nvarchar(60) , content ntext ); Test content. insert into content (dept_id, page_name, content) values (3, 'index', '<h2>welcome to department 3!</h2>'); insert into content (dept_id, page_name, content) values (4, 'index', '<h2>welcome to department 3.1!</h2>'); insert into content (dept_id, page_name, content) values (6, 'index', '<h2>welcome to department 3.2.1!</h2>'); insert into content (dept_id, page_name, content) values (2, 'what-doing', '<h2>what is department 2 doing?/h2>'); I'm trying to query the correct page content (from the content table) based on the url given. I can easily accomplish this task with a root department. However, querying a department with multiple depths is proving to be a little harder. For example: http://localhost/departments.asp?d3/ (Should return <h2>welcome to department 3!</h2>) http://localhost/departments.asp?d2/what-doing (Should return <h2>what is department 2 doing?</h2>) I'm not sure if this can be create in one query or if there will need to be a recursive function of some sort. Also, if there is nothing after the last / then assume we want the index page. How can this be accomplished? Thank you.

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  • How can I delete ghost database field between a special date?

    - by Chiyou
    I have a mysql table with many user input and I want to delete ghost e-mail between a special date. I use this query and it seems to work very good: DELETE u1 From tx_table u1 JOIN tx_table u2 USING (email) WHERE u1.tstamp < u2.tstamp but I want to delete between a longer time. When I add 300 it seems to delete everything in my table: DELETE u1 From tx_table u1 JOIN tx_table u2 USING (email) WHERE u1.tstamp < u2.tstamp+300. How can I add 5 minutes to the tstamp with SQL?

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  • How do you optimize database performance when providing results for autocomplete/iterative search?

    - by Howiecamp
    Note: In this question I'm using the term "autocomplete" (or "iterative search") to refer to returning search-as-you-type results, e.g. like Google Search gives you. Also my question is not specific to web applications vs. fat client apps. How are SQL SELECT queries normally constructed to provide decent performance for this type of query, especially over arbitrarily large data sets? In the case where the search will only query based on the first n characters (easiest case) am I still issuing a new SELECT result FROM sometable WHERE entry LIKE... on each keypress. Even with various forms of caching this seems like it might result in poor performance. In cases where you want your search string to return results with prefix matches, substring matches, etc. it's an even more difficult problem. Looking at a case of searching a list of contacts, you might return results that match FirstName + LastName, LastName + FirstName, or any other substring.

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  • Can I change the datsource of report model at runtime

    - by Manab De
    I've some adhoc reports developed on some report models which are published on Report Server (we're using SSRS 2008). Everything is running well. Now in our production environment we've near about forty (40) customers who have their own database (each have the same table structures and other database objects). Now the challenge is whenever a customer will log into the report server using windows authentication and trying to view those reports we need to get the SQL data from the proper database only. Reports are designed using the report model and each model has a valid data source which is connected to particular database. We can create forty separate data sources each will be connected to specific database. My question is, is there any way through which we can change the report model data source name dynamically or during runtime based on the customer name so that during execution of the report, SSRS would fetch the data from the correct database but not from any other database. Please help me.

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  • How to display only selected data in combo box at run time from database?

    - by Joy1979
    I am new to .Net and I am working on one task. Below is my scenario. I have 2 tables: Table 1: Students StudentID StudentDetail 1 StudentName 2 StudentGrade Table 2: Student_data StudentDetail StudentRecords StudentName John (Default) StudentName Jacob StudentName Smith StudentGrade A (default) StudentGrade B StudentGrade C Question: When window form loads (run time) I need to display StudentRecords in combo box with StudentName = "John" and StudentGrade = "A" as default followed by other values. StudentName and StudentRecords are in Labels and values are in a ComboBox. I am using VB.Net and VS 2010 with SQL 2008r2. I would appreciate any step by step help. Apologies If my request is simple.

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  • PHP looping through an array to fetch a value for each key from database (third normal form)

    - by zomboble
    I am building a system, mostly for consolidating learning but will be used in practice. I will try and verbally explain the part of the E-R diagram I am focusing on: Each cadet can have many uniformID's Each Uniform ID is a new entry in table uniform, so cadets (table) may look like: id | name | ... | uniformID 1 | Example | ... | 1,2,3 uniform table: id | notes | cadet 1 | Need new blahh | 1 2 | Some stuff needed | 1 3 | Whatever you like | 1 On second thought, looks like I wont need that third column in the db. I am trying to iterate through each id in uniformID, code: <?php $cadet = $_GET['id']; // set from URL $query = mysql_query("SELECT `uniformID` FROM `cadets` WHERE id = '$cadet' LIMIT 1") or die(mysql_error()); // get uniform needed as string // store it while ($row = mysql_fetch_array($query)) { $uniformArray = $row['uniformID']; } echo $uniformArray . " "; $exploded = explode(",", $uniformArray); // convert into an array // for each key in the array perform a new query foreach ($exploded as $key => $value) { $query(count($exploded)); $query[$key] = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); } ? As I say, this is mainly for consolidation purposes but I have come up with a error, sql is saying: Fatal error: Function name must be a string in C:\wamp\www\intranet\uniform.php on line 82 line 82 is: $query[$key] = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); I wasn't sure it would work so I tried it and now i'm stuck! EDIT: Thanks to everyone who has contributed to this! This is now the working code: foreach ($exploded as $key => $value) { //$query(count($exploded)); $query = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); while ($row = mysql_fetch_array($query)) { echo "<tr> <td>" . $row['id'] . "</td> <td>" . $row['note'] . "</td> </tr>"; } } Added the while and did the iteration by nesting it in the foreach

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