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  • How to avoid multiple, unused has_many associations when using multiple models for the same entity (

    - by mikep
    Hello, I'm looking for a nice, Ruby/Rails-esque solution for something. I'm trying to split up some data using multiple tables, rather than just using one gigantic table. My reasoning is pretty much to try and avoid the performance drop that would come with having a big table. So, rather than have one table called books, I have multiple tables: books1, books2, books3, etc. (I know that I could use a partition, but, for now, I've decided to go the 'multiple tables' route.) Each user has their books placed into a specific table. The actual book table is chosen when the user is created, and all of their books go into the same table. The goal is to try and keep each table pretty much even -- but that's a different issue. One thing I don't particularly want to have is a bunch of unused associations in the User class. Right now, it looks like I'd have to do the following: class User < ActiveRecord::Base has_many :books1, :books2, :books3, :books4, :books5 end class Books1 < ActiveRecord::Base belongs_to :user end class Books2 < ActiveRecord::Base belongs_to :user end First off, for each specific user, only one of the book tables would be usable/applicable, since all of a user's books are stored in the same table. So, only one of the associations would be in use at any time and any other has_many :bookX association that was loaded would be a waste. I don't really know Ruby/Rails does internally with all of those has_many associations though, so maybe it's not so bad. But right now I'm thinking that it's really wasteful, and that there may just be a better, more efficient way of doing this. Is there's some sort of special Ruby/Rails methodology that could be applied here to avoid having to have all of those has_many associations? Also, does anyone have any advice on how to abstract the fact that there's multiple book tables behind a single books model/class?

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  • Is there any way to create a dynamic list of strings (based on language) in XAML?

    - by Xin
    Just wondering if it is possible to dynamically create a list of strings in XAML based on language/culture? Say if user logs in as an English user it shows Client Name, Order Number... and if user logs in as a Polish user it shows Nazwa klienta, Numer zamówienia instead? I only know the hardcoded one like below: <System_Collections_Generic:List`1 x:Key="columnNameList"> <System:String>Client Name</System:String> <System:String>Order Number</System:String> <System:String>Date</System:String> </System_Collections_Generic:List`1>

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  • Problem writing HTML content to Word document in ASP.NET

    - by saran
    I am trying to export the HTML page contents to Word. My Html display page is: What is your favourite color? NA List the top three school ? one National two Devs three PS And a button for click event. The button click event will open MS word and paste the page contents in word. The word page contains the table property of html design page. It occurs only in Word 2003. But in word 2007 the word document contains the text with out table property. How can I remove this table property in word 2003. I am not able to add the snapshots. Else i will make you clear. I am designing the web page by aspx. I am exporting the web page content by the following code. protected void Button1_Click(object sender, EventArgs e) { Response.ContentEncoding = System.Text.Encoding.UTF7; System.Text.StringBuilder SB = new System.Text.StringBuilder(); System.IO.StringWriter SW = new System.IO.StringWriter(); System.Web.UI.HtmlTextWriter htmlTW = new System.Web.UI.HtmlTextWriter(SW); tbl.RenderControl(htmlTW); string strBody = "<html>" + "<body>" + "<div><b>" + htmlTW.InnerWriter.ToString() + "</b></div>" + "</body>" + "</html>"; Response.AppendHeader("Content-Type", "application/msword"); Response.AppendHeader("Content-disposition", "attachment; filename=" + fileName); Response.ContentEncoding = System.Text.Encoding.UTF7; string fileName1 = "C://Temp/Excel" + DateTime.Now.Millisecond.ToString(); BinaryWriter writer = new BinaryWriter(File.Open(fileName1, FileMode.Create)); writer.Write(strBody); writer.Close(); FileStream fs = new FileStream(fileName1, FileMode.Open, FileAccess.Read); byte[] renderedBytes; // Create a byte array of file stream length renderedBytes = new byte[fs.Length]; //Read block of bytes from stream into the byte array fs.Read(renderedBytes, 0, System.Convert.ToInt32(fs.Length)); //Close the File Stream fs.Close(); FileInfo TheFile = new FileInfo(fileName1); if (TheFile.Exists) { File.Delete(fileName1); } Response.BinaryWrite(renderedBytes); Response.Flush(); Response.End(); }

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  • User Control as container at design time

    - by Luca
    I'm designing a simple expander control. I've derived from UserControl, drawn inner controls, built, run; all ok. Since an inner Control is a Panel, I'd like to use it as container at design time. Indeed I've used the attributes: [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] Great I say. But it isn't... The result is that I can use it as container at design time but: The added controls go back the inner controls already embedded in the user control Even if I push to top a control added at design time, at runtime it is back again on controls embedded to the user control I cannot restrict the container area at design time into a Panel area What am I missing? Here is the code for completeness... why this snippet of code is not working? [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] public partial class ExpanderControl : UserControl { public ExpanderControl() { InitializeComponent(); .... [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] internal class ExpanderControlDesigner : ControlDesigner { private ExpanderControl MyControl; public override void Initialize(IComponent component) { base.Initialize(component); MyControl = (ExpanderControl)component; // Hook up events ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); s.SelectionChanged += new EventHandler(OnSelectionChanged); c.ComponentRemoving += new ComponentEventHandler(OnComponentRemoving); } private void OnSelectionChanged(object sender, System.EventArgs e) { } private void OnComponentRemoving(object sender, ComponentEventArgs e) { } protected override void Dispose(bool disposing) { ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); // Unhook events s.SelectionChanged -= new EventHandler(OnSelectionChanged); c.ComponentRemoving -= new ComponentEventHandler(OnComponentRemoving); base.Dispose(disposing); } public override System.ComponentModel.Design.DesignerVerbCollection Verbs { get { DesignerVerbCollection v = new DesignerVerbCollection(); v.Add(new DesignerVerb("&asd", new EventHandler(null))); return v; } } } I've found many resources (Interaction, designed, limited area), but nothing was usefull for being operative... Actually there is a trick, since System.Windows.Forms classes can be designed (as usual) and have a correct behavior at runtime (TabControl, for example).

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  • How can you tell the source of the data when using the Stream.BeginRead Method?

    - by xarzu
    When using the Stream.BeginRead Method, and you are reading from a stream into a memory, how is it determined where you are reading the data from? See: http://msdn.microsoft.com/en-us/library/system.io.stream.beginread.aspx In the list of parameters, I do not see one that tells where the data is being read from: Parameters buffer Type: System.Byte[] The buffer to read the data into. offset Type: System.Int32 The byte offset in buffer at which to begin writing data read from the stream. count Type: System.Int32 The maximum number of bytes to read. callback Type: System.AsyncCallback An optional asynchronous callback, to be called when the read is complete. state Type: System.Object A user-provided object that distinguishes this particular asynchronous read request from other requests.

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  • Are GUID primary keys bad in theory, or just practice?

    - by Yarin
    Whenever I design a database I automatically start with an auto-generating GUID primary key for each of my tables (excepting look-up tables) I know I'll never lose sleep over duplicate keys, merging tables, etc. To me it just makes sense philosophically that any given record should be unique across all domains, and that that uniqueness should be represented in a consistent way from table to table. I realize it will never be the most performant option, but putting performance aside, I'd like to know if there are philosophical arguments against this practice?

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  • Is there an ORM that supports composition w/o Joins

    - by Ken Downs
    EDIT: Changed title from "inheritance" to "composition". Left body of question unchanged. I'm curious if there is an ORM tool that supports inheritance w/o creating separate tables that have to be joined. Simple example. Assume a table of customers, with a Bill-to address, and a table of vendors, with a remit-to address. Keep it simple and assume one address each, not a child table of addresses for each. These addresses will have a handful of values in common: address 1, address 2, city, state/province, postal code. So let's say I'd have a class "addressBlock" and I want the customers and vendors to inherit from this class, and possibly from other classes. But I do not want separate tables that have to be joined, I want the columns in the customer and vendor tables respectively. Is there an ORM that supports this? The closest question I have found on StackOverflow that might be the same question is linked below, but I can't quite figure if the OP is asking what I am asking. He seems to be asking about foregoing inheritance precisely because there will be multiple tables. I'm looking for the case where you can use inheritance w/o generating the multiple tables. Model inheritance approach with Django's ORM

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  • Request for comments: Ruby script that counts the length of a MySQL table name

    - by bakerjr
    Hi, I'm new at ruby and I would like to ask you guys if there's something that could improve my Ruby code. Here's my script: #!/usr/bin/ruby -w require 'mysql' dbh = Mysql.real_connect('localhost', 'db_user', 'password', 'db_table') tables = dbh.query('show tables') tables.each do |table| puts "#{table}" + " (" + "#{table}".length.to_s + ")" end I'd love to hear your comments. Thanks in advance

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  • Negative Primary Keys

    - by bjax
    Are there any repercussions using Negative Primary Keys for tables (Identity Increment -1, Identity Seed -1 in SQL Server 2005)? The reason for this is we're creating a new database to replace an existing one. There are similar tables between the two databases and we'd like the "source" of the information to be transparent to our applications. The approach is to create views that unions tables from both databases. Negative PKs ensures the identities don't overlap.

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  • TCPClient in C# (Error).

    - by CSharp
    using System; using System.Text; using System.IO; using System.Net.Sockets; namespace ConsoleApp01 { class Program { public static void Main(string[] args) { TcpClient client = new TcpClient("python.org",80); NetworkStream ns = client.GetStream(); StreamWriter sw = new StreamWriter(ns); sw.Write("HEAD / HTTP/1.1\r\n" + "User-Agent: Test\r\n" + "Host: www.python.org\r\n" + "Connection: Close\r\n"); sw.Flush(); Console.ReadKey(true); } } } System.Net.Sockets.SocketException: Unable to make a connection because the target machine actively refused it at System.Net.Sockets.TcpClient..ctor at ConsoleApp01.Program.Main :line 12 Why do i get this error message?

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  • Can't Use Generic C# Class in Using Statement

    - by Eric J.
    I'm trying to use a generic class in a using statement but the compiler can't seem to treat it as implementing IDisposable. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data.Objects; namespace Sandbox { public sealed class UnitOfWorkScope<T> where T : ObjectContext, IDisposable, new() { public void Dispose() { } } public class MyObjectContext : ObjectContext, IDisposable { public MyObjectContext() : base("DummyConnectionString") { } #region IDisposable Members void IDisposable.Dispose() { throw new NotImplementedException(); } #endregion } public class Consumer { public void DoSomething() { using (new UnitOfWorkScope<MyObjectContext>()) { } } } } Compiler error is: Error 1 'Sandbox.UnitOfWorkScope<Sandbox.MyObjectContext>': type used in a using statement must be implicitly convertible to 'System.IDisposable' I implemented IDisposable on UnitOfWorkScope (and to see if that was the problem, also on MyObjectContext). What am I missing?

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  • SqlServer2008 + expensive union

    - by Tim Mahy
    Hi al, we have 5 tables over which we should query with user search input throughout a stored procedure. We do a union of the similar data inside a view. Because of this the view can not be materialized. We are not able to change these 5 tables drastically (like creating a 6th table that contains the similar data of the 5 tables and reference that new one from the 5 tables). The query is rather expensive / slow what are our other options? It's allowed to think outside the box. Unfortunately I cannot give more information like the table/view/SP definition because of customer confidentiality... greetings, Tim

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  • An image from byte to optimized web page presentation

    - by blgnklc
    I get the data of the stored image on database as byte[] array; then I convert it to System.Drawing.Image like the code shown below; public System.Drawing.Image CreateImage(byte[] bytes) { System.IO.MemoryStream memoryStream = new System.IO.MemoryStream(bytes); System.Drawing.Image image = System.Drawing.Image.FromStream(memoryStream); return image; } (*) On the other hand I am planning to show a list of images on asp.net pages as the client scrolls downs the page. The more user gets down and down on the page he/she does see the more photos. So it means fast page loads and rich user experience. (you may see what I mean on www.mashable.com, just take care the new loads of the photos as you scroll down.) Moreover, the returned imgae object from the method above, how can i show it in a loop dynamically using the (*) conditions above. Regards bk

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  • protobuf-net NOT faster than binary serialization?

    - by Ashish Gupta
    I wrote a program to serialize a 'Person' class using XMLSerializer, BinaryFormatter and ProtoBuf. I thought protobuf-net should be faster than the other two. Protobuf serialization was faster than XMLSerialization but much slower than the binary serialization. Is my understanding incorrect? Please make me understand this. Thank you for the help. Following is the output:- Person got created using protocol buffer in 347 milliseconds Person got created using XML in 1462 milliseconds Person got created using binary in 2 milliseconds Code below using System; using System.Collections.Generic; using System.Linq; using System.Text; using ProtoBuf; using System.IO; using System.Diagnostics; using System.Runtime.Serialization.Formatters.Binary; namespace ProtocolBuffers { class Program { static void Main(string[] args) { string XMLSerializedFileName = "PersonXMLSerialized.xml"; string ProtocolBufferFileName = "PersonProtocalBuffer.bin"; string BinarySerializedFileName = "PersonBinary.bin"; var person = new Person { Id = 12345, Name = "Fred", Address = new Address { Line1 = "Flat 1", Line2 = "The Meadows" } }; Stopwatch watch = Stopwatch.StartNew(); watch.Start(); using (var file = File.Create(ProtocolBufferFileName)) { Serializer.Serialize(file, person); } watch.Stop(); Console.WriteLine(watch.ElapsedMilliseconds.ToString()); Console.WriteLine("Person got created using protocol buffer in " + watch.ElapsedMilliseconds.ToString() + " milliseconds " ); watch.Reset(); watch.Start(); System.Xml.Serialization.XmlSerializer x = new System.Xml.Serialization.XmlSerializer(person.GetType()); using (TextWriter w = new StreamWriter(XMLSerializedFileName)) { x.Serialize(w, person); } watch.Stop(); Console.WriteLine(watch.ElapsedMilliseconds.ToString()); Console.WriteLine("Person got created using XML in " + watch.ElapsedMilliseconds.ToString() + " milliseconds"); watch.Reset(); watch.Start(); using (Stream stream = File.Open(BinarySerializedFileName, FileMode.Create)) { BinaryFormatter bformatter = new BinaryFormatter(); //Console.WriteLine("Writing Employee Information"); bformatter.Serialize(stream, person); } watch.Stop(); Console.WriteLine(watch.ElapsedMilliseconds.ToString()); Console.WriteLine("Person got created using binary in " + watch.ElapsedMilliseconds.ToString() + " milliseconds"); Console.ReadLine(); } } [ProtoContract] [Serializable] public class Person { [ProtoMember(1)] public int Id {get;set;} [ProtoMember(2)] public string Name { get; set; } [ProtoMember(3)] public Address Address {get;set;} } [ProtoContract] [Serializable] public class Address { [ProtoMember(1)] public string Line1 {get;set;} [ProtoMember(2)] public string Line2 {get;set;} } }

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  • How to model a mutually exclusive relationship in sql server

    - by littlechris
    Hi, I have to add functionality to an existing application and I've run into a data situation that I'm not sure how to model. I am being restricted to the creation of new tables and code. If I need to alter the existing structure I think my client may reject the proposal..although if its the only way to get it right this is what I will have to do. I have an Item table that can me link to any number of tables, and these tables may increase over time. The Item can only me linked to one other table, but the record in the other table may have many items linked to it. Examples of the tables/entities being linked to are "Person", "Vehicle", "Building", "Office". These are all separate tables. Example of Items are "Pen", "Stapler", "Cushion", "Tyre", "A4 Paper", "Plastic Bag", "Poster", "Decoration" For instance a "Poster" may be allocated to a "Person" or "Office" or "Building". In the future if they add a "Conference Room" table it may also be added to that. My intital thoughts are: Item { ID, Name } LinkedItem { ItemID, LinkedToTableName, LinkedToID } The LinkedToTableName field will then allow me to identify the correct table to link to in my code. I'm not overly happy with this solution, but I can't quite think of anything else. Please help! :) Thanks!

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  • How to isolate data per customer, Django powered website

    - by Sawwy
    I have recently started learning python and django and working on a project that includes building a website for collecting information from customers. I am currently trying to figure out best way to isolate the customer data (collected information is sensitive and should only be accessible by customer and the service provider). I found this post Postgresql - one database for everyone, or one-database per customer and my question is that can I automate the model inheritance with customer creation via admin? To be specific, when save() is called for adding customer via django admin, this should create the customer specific tables (create a new set of tables with 'company_name' -prefix). For more information of the environment, I have extended the basic user registration with custom UserProfile adding 'company' and 'role' fields for each user. Upon login, the 'company' of the user will be checked to filter out tables without the 'company_name' prefix. 'Role' will further filter the which company-specific tables and set rights (view, edit). will appreciate any suggestions if more elegant methods could be used to solve the data isolation problem than model inheritance.

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  • Hibernate question hbm2ddl.auto possible values and what they do

    - by Suzan
    I really want to know more about the update, export and the values that could be given to hbm2ddl.auto. I need to know when to use the update and when not? And what is the alternative? These are changes that could happen over DB: New tables new columns in old tables columns deleted data type of a column changed a type of a column changed it attributes tables have been dropped values of a column has changed In each case what is the best solution?

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  • SqlServer2008 + expensive union all

    - by Tim Mahy
    Hi al, we have 5 tables over which we should query with user search input throughout a stored procedure. We do a union all of the similar data inside a view. Because of this the view can not be materialized. We are not able to change these 5 tables drastically (like creating a 6th table that contains the similar data of the 5 tables and reference that new one from the 5 tables). The query is rather expensive / slow what are our other options? It's allowed to think outside the box. Unfortunately I cannot give more information like the table/view/SP definition because of customer confidentiality... greetings, Tim

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  • What are the reasons *not* to use a GUID for a primary key?

    - by Yarin
    Whenever I design a database I automatically start with an auto-generating GUID primary key for each of my tables (excepting look-up tables) I know I'll never lose sleep over duplicate keys, merging tables, etc. To me it just makes sense philosophically that any given record should be unique across all domains, and that that uniqueness should be represented in a consistent way from table to table. I realize it will never be the most performant option, but putting performance aside, I'd like to know if there are philosophical arguments against this practice?

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  • How to execute commands in Command Prompt using c#

    - by karthik
    I want to execute these steps in CMD using c# 1 - CD C:\MySQL\MySQL Server 5.0\bin 2 - mysqldump -uroot -ppassword sample d:\Test\222.sql On manually doing this, i will get file named "222.sql" I am using the below code to do it, but missing something.. Nothing Happens public void CreateScript_AAR() { string commandLine = @"CD C:\MySQL\MySQL Server 5.0\bin\mysqldump -uroot -ppassword sample> d:\Test\222.sql"""; System.Diagnostics.ProcessStartInfo PSI = new System.Diagnostics.ProcessStartInfo("cmd.exe"); PSI.RedirectStandardInput = true; PSI.RedirectStandardOutput = true; PSI.RedirectStandardError = true; PSI.UseShellExecute = false; System.Diagnostics.Process p = System.Diagnostics.Process.Start(PSI); System.IO.StreamWriter SW = p.StandardInput; System.IO.StreamReader SR = p.StandardOutput; SW.WriteLine(commandLine); SW.Close(); }

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  • Using an ORM with a database that has no defined relationships?

    - by Ahmad
    Consider a database(MSSQL 2005) that consists of 100+ tables which have primary keys defined to a certain degree. There are 'relationships' between tables, however these are not enforced with foreign key constraints. Consider the following simplified example of typical types of tables I am dealing with. The are clear relations between the User and City and Province tables. However, they key issues is the inconsistent data types in the tables and naming conventions. User: UserRowId [int] PK Name [varchar(50)] CityId [smallint] ProvinceRowId [bigint] City: CityRowId [bigint] PK CityDescription [varchar(100)] Province: ProvinceId [int] PK ProvinceDesc [varchar(50)] I am considering a rewrite of the application (in ASP.net MVC) that uses this data source as is similar in design to MVC storefront. However I am going through a proof of concept phase and this is one of the stumbling blocks I have come across. What are my options in terms of ORM choice that can be easily used and why? Should I even be considering an ORM? (The reason I ask this is that most explanations and tutorials all work with relatively cleanly designed existing databases, or newly created ones when compared to mine. I am thus having a very hard time trying to find a way forward with this problem) There is a huge amount of existing SQL queries, would a datamappper(eg IBatis.net) be more suitable since we could easily modify them to work and reuse the investment already made? I have found this question on SO which indicates to me that an ORM can be used - however I get the impression that this a question of mapping? Note: at the moment, the object model is not clearly defined as it was non-existent. The existing system pretty much did almost everything in SQL or consisted of overly complicated, and numerous queries to complete fucntionality. I am pretty much a noob and have zero experience around ORMs and MVC - so this an awesome learning curve I am on.

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  • What could possibly be different between the table in a DataContext and an IQueryable<Table> when do

    - by Nate Bross
    I have a table, where I need to do a case insensitive search on a text field. If I run this query in LinqPad directly on my database, it works as expected Table.Where(tbl => tbl.Title.Contains("StringWithAnyCase") In my application, I've got a repository which exposes IQueryable objects which does some initial filtering and it looks like this var dc = new MyDataContext(); public IQueryable<Table> GetAllTables() { var ret = dc.Tables.Where(t => t.IsActive == true); return ret; } In the controller (its an MVC app) I use code like this in an attempt to mimic the LinqPad query: var rpo = new RepositoryOfTable(); var tables = rpo.GetAllTables(); // for some reason, this does a CASE SENSITIVE search which is NOT what I want. tables = tables.Where(tbl => tbl.Title.Contains("StringWithAnyCase"); return View(tables); The column is defiend as an nvarchar(50) in SQL Server 2008. Any help or guidance is greatly appreciated!

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  • Database Modelling - Conceptually different entities with near identical fields

    - by Andrew Shepherd
    Suppose you have two sets of conceptual entities: MarketPriceDataSet which has multiple ForwardPriceEntries PoolPriceForecastDataSet which has multiple PoolPriceForecastEntry Both different child objects have near identical fields: ForwardPriceEntry has StartDate EndDate SimulationItemId ForwardPrice MarketPriceDataSetId (foreign key to parent table) PoolPriceForecastEntry has StartDate EndDate SimulationItemId ForecastPoolPrice PoolPriceForecastDataSetId (foreign key to parent table) If I modelled them as separate tables, the only difference would be the foreign key, and the name of the price field. There has been a debate as to whether the two near identical tables should be merged into one. Options I've thought of to model this is: Just keep them as two independent, separate tables Have both sets in the one table with an additional "type" field, and a parent_id equalling a foreign key to either parent table. This would sacrifice referential integrity checks. Have both sets in the one table with an additional "type" field, and create a complicated sequence of joining tables to maintain referential integrity. What do you think I should do, and why?

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