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  • How can I improve the performance of LinqToSql queries that use EntitySet properties?

    - by DanM
    I'm using LinqToSql to query a small, simple SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of what makes LinqToSql so appealing. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance besides resorting to doing all the joins manually? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view. Update Here are the table definitions for the example I used in my question: create table Order ( Id int identity(1, 1) primary key, ProductName ntext null ) create table Customer ( Id int identity(1, 1) primary key, OrderId int null references Order (Id) )

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  • Regarding some Update Stored procedure

    - by Serenity
    I have two Tables as follows:- Table1:- ------------------------------------- PageID|Content|TitleID(FK)|LanguageID ------------------------------------- 1 |abc |101 |1 2 |xyz |102 |1 -------------------------------------- Table2:- ------------------------- TitleID|Title |LanguageID ------------------------- 101 |Title1|1 102 |Title2|1 ------------------------ I don't want to add duplicates in my Table1(Content Table). Like..there can be no two Pages with the same Title. What check do I need to add in my Insert/Update Stored Procedure ? How do I make sure duplicates are never added. I have tried as follows:- CREATE PROC InsertUpdatePageContent ( @PageID int, @Content nvarchar(2000), @TitleID int ) AS BEGIN IF(@PageID=-1) BEGIN IF(NOT EXISTS(SELECT TitleID FROM Table1 WHERE LANGUAGEID=@LANGUAGEID)) BEGIN INSERT INTO Table1(Content,TitleID) VALUES(@Content,@TitleID) END END ELSE BEGIN IF(NOT EXISTS(SELECT TitleID FROM Table1 WHERE LANGUAGEID=@LANGUAGEID)) BEGIN UPDATE Table1 SET Content=@Content,TitleID=@TitleID WHERE PAGEID=@PAGEID END END END Now what is happening is that it is inserting new records alright and won't allow duplicates to be added but when I update its giving me problem. On my aspx Page I have a drop down list control that is bound to DataSource that returns Table 2(Title Table) and I have a text box in which user types Page's content to be stored. When I update, like lets say I have a row in my Table 1 as shown above with PageID=1. Now when I am updating this row, like I didn't change the Title from the drop down and only changed Content in the text box, its not updating the record ..and when Stored procedure's Update Query does not execute it displays a Label that says "Page with this title exists already." So whenever I am updating an existing record that label is displayed on screen.How do I change that IF condition in my Update Stored procedure?? EDIT:- @gbn :: Will that IF condition work in case of update? I mean lets say I am updating the Page with TitleID=1, I changed its content, then when I update, it's gonna execute that IF condition and it still won't update coz TitleID=1 already exits!It will only update if TitleID=1 is not there in Table1. Isn't it? Guess I am getting confused. Please answer.Thanks.

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  • Stored Procedures In Source Control - Automate Build/Deployment Process

    - by Alex
    My company provides a large .NET service-oriented solution. The services layer interact with a T-SQL back-end consisting of hundreds of tables and stored procedures. Our C# code is in version-control (SVN) but our stored procedures and schema are not. After much lobbying of expedient upper-management, I was allowed to review our (non-existent) build/deployment process to accomplish the following goals: Place schema and stored procedures under source-control. Automate the build/deployment process. I would like to proceed per the accepted answer's strategy in this post but have additional questions: I would like to use Hudson as my build server. Is this a reasonable choice for a C#/SQL solution? What better alternatives should I explore? Assuming I have all triggers, stored-procedures, schema, etc... under source control, and that they are scripted to individual files, how do I generate a build script which will take into account dependencies/references between these items? (SQL Server does this automatically, but it generates one giant script) What does the workflow of performing an update at the client look like? i.e. I have to keep existing table data. How do I roll-back schema changes? I am the only programmer. Several other pseudo-technical staff like to make changes directly inside SQL Management Studio. Is it realistic to expect others to adhere to this solution -- how can I enforce this? Thank you in advance for your help.

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  • Association Mapping Details confusion?

    - by AaronLS
    I have never understood why the associations in EntityFramework look the way they do in the Mapping Details window. When I select the line between 2 tables for an association, for example FK_ApplicationSectionsNodes_FormItems, it shows this: Association Maps to ApplicationSectionNodes FormItems (key symbol) FormItemId:Int32 <--> FormItemId:int ApplicationSectionNodes (key symbol) NodeId:Int32 <--> (key symbol) NodeId : int Fortunately this one was create automatically for me based on the foreign key constraints in my database, but whenever no constraints exist, I have a hard to creating associations manually(when the database doesn't have a diagram setup) because I don't understand the mapping details for associations. FormItems table has a primary key identity column FormItemId, and ApplicationSectionNodes contains a FormItemId column that is the foreign key and has NodeId as a primary key identity column. What really makes no sense to me is why the association has anything listed about the NodeId, when NodeId doesn't have anything to do with the foreign key relationship? (It's even more confusing with self referencing relationships, but maybe if I could understand the above case I'd have a better handle). CREATE TABLE [dbo].[ApplicationSectionNodes]( [NodeID] [int] IDENTITY(1,1) NOT NULL, [OutlineText] [varchar](5000) NULL, [ParentNodeID] [int] NULL, [FormItemId] [int] NULL, CONSTRAINT [PK_ApplicationSectionNodes] PRIMARY KEY CLUSTERED ( [NodeID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY], CONSTRAINT [UQ_ApplicationSectionNodesFormItemId] UNIQUE NONCLUSTERED ( [FormItemId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[ApplicationSectionNodes] WITH NOCHECK ADD CONSTRAINT [FK_ApplicationSectionNodes_ApplicationSectionNodes] FOREIGN KEY([ParentNodeID]) REFERENCES [dbo].[ApplicationSectionNodes] ([NodeID]) GO ALTER TABLE [dbo].[ApplicationSectionNodes] NOCHECK CONSTRAINT [FK_ApplicationSectionNodes_ApplicationSectionNodes] GO ALTER TABLE [dbo].[ApplicationSectionNodes] WITH NOCHECK ADD CONSTRAINT [FK_ApplicationSectionNodes_FormItems] FOREIGN KEY([FormItemId]) REFERENCES [dbo].[FormItems] ([FormItemId]) GO ALTER TABLE [dbo].[ApplicationSectionNodes] NOCHECK CONSTRAINT [FK_ApplicationSectionNodes_FormItems] GO FormItems Table: CREATE TABLE [dbo].[FormItems]( [FormItemId] [int] IDENTITY(1,1) NOT NULL, [FormItemType] [int] NULL, CONSTRAINT [PK_FormItems] PRIMARY KEY CLUSTERED ( [FormItemId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[FormItems] WITH NOCHECK ADD CONSTRAINT [FK_FormItems_FormItemTypes] FOREIGN KEY([FormItemType]) REFERENCES [dbo].[FormItemTypes] ([FormItemTypeId]) GO ALTER TABLE [dbo].[FormItems] NOCHECK CONSTRAINT [FK_FormItems_FormItemTypes] GO

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  • Populate an unmapped property of domain object from result of join with Nhibernate

    - by Adam Pope
    I have a situation where I have 3 tables: StockItem, Office and StockItemPrice. The price for each StockItem can be different for each Office. StockItem( ID Name ) Office( ID Name ) StockItemPrice( ID StockItemID OfficeID Price ) I've set up a schema with 2 many-to-one relations to link StockItem and Office. So in my StockItem domain object I have a property: IList<StockItemPrice> Prices; which gets loaded with the price of the item for each office. That's working fine. Now I'm trying to get the price of an item for a single office. I have the following Criteria query: NHibernateSession.CreateCriteria(persistentType) .Add(Restrictions.Eq("ID", id)) .CreateAlias("Prices", "StockItemPrice") .Add(Restrictions.Eq("StockItemPrice.Office", office)) .UniqueResult<StockItem>(); This appears to work fine as the SQL it generates is what I qould expect. However, I dont know if it populates StockItem.Prices with a single object correctly as as soon as I reference that property NHibernate performs a lazy load of all the office's prices. Also, even if it does work, it feels really crufty having to access the price by using: mystockitem.Prices[0].Price What I would really like is to have a Price field on the StockItem object and have the price of the item put into that field by NHibernate. I've tried adding .CreateCriteria("Price", "StockItemPrice.Price") and the same with CreateAlias, but I get the error NHibernate.QueryException : could not resolve property: Price of: StockItem which makes sense I guess as Price isn't a mapped property. How would I adjust the query to make this possible?

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  • Database abstraction/adapters for ruby

    - by Stiivi
    What are the database abstractions/adapters you are using in Ruby? I am mainly interested in data oriented features, not in those with object mapping (like active record or data mapper). I am currently using Sequel. Are there any other options? I am mostly interested in: simple, clean and non-ambiguous API data selection (obviously), filtering and aggregation raw value selection without field mapping: SELECT col1, col2, col3 = [val1, val2, val3] not hash of { :col1 = val1 ...} API takes into account table schemas 'some_schema.some_table' in a consistent (and working) way; also reflection for this (get schema from table) database reflection: get list of table columns, their database storage types and perhaps adaptor's abstracted types table creation, deletion be able to work with other tables (insert, update) in a loop enumerating selection from another table without requiring to fetch all records from table being enumerated Purpose is to manipulate data with unknown structure at the time of writing code, which is the opposite to object mapping where structure or most of the structure is usually well known. I do not need the object mapping overhead. What are the options, including back-ends for object-mapping libraries?

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  • How create single HTML file to viewed in Excel with multiple sheets?

    - by Dmitry Nelepov
    I want know, is it possible create single HTML file wich (after chaging extension to xls) when opened at Excel will parsed to multiple sheets. Little example i got file test.xls with contents <html> <body> <table> <tr> <td> 1 </td> <td> 2 </td> <td> 3 </td> <td> =sum(A1:C1) </td> </tr> </table> </body> </html> When i open this file at Excel i got one Sheet with calculated sum of cells A1 to C1 in A4=6 I wonder, it's possible create a HTML file wich containts multiple tables wich will be parsed as multiple sheets at Excel. Here Excel view of this file

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  • How to create XSD schema from XML with this kind of structure (in .net)?

    - by Mr. Brownstone
    Here's the problem: my input is XML file that looks something like: <BaseEntityClassInfo> <item> <key>BaseEntityClassInfo.SomeField</key> <value>valueData1</value> </item> <item> <key>BaseEntityClassInfo.AdditionalDataClass.SomeOtherField</key> <value>valueData2</value> </item> <item> <key>BaseEntityClassInfo.AdditionalDataClass.AnotherClassInfo.DisplayedText</key> <value>valueData3</value> </item> ... ... </BaseEntityClassInfo> The <key> element somehow describes entity classes fields and relationships (used in some other app that I don't have access to) and the <value> stores the actual data that I need. My goal is to programatically generate a typed Dataset from this XML that could then be used for creating reports. I thought of building some XSD schema from input XML file first and then use this schema to generate Dataset but I'm not sure how to do that. The problem is that I don't want all data in one table, I need several tables with relationships based on the <key> value so I guess I need to infer relational structure from XML <key> data in some way. So what do you think? How could this be done and what would be the best approach? Any advice, ideas, suggestions would be appreciated!

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  • how to make a software and preserve database integrity and correctness and please help confused

    - by user287745
    i have made an application project in vs 08 c#, sql server from vs 08. the database has like 20 tables and many fields in each have made an interface for adding deleting editting and retrieving data according to predefined needs of the users. now i have to 1) make to project in to a software which i can deliver to professor. that is he can just double click the icon and the software simply starts. no vs 08 needed to start the debugging 2) the database will be on one powerful computer (dual core latest everything win xp) and the user will access it from another computer connected using LAN i am able to change the connection string to the shared database using vs 08/ debugger whenever the server changes but how am i supposed to do that when its a software? 3)there will by many clients am i supposed to give the same software to every one, so they all can connect to the database, how will the integrity and correctness of the database be maintained? i mean the db.mdf file will be in a folder which will be shared with read and write access. so its not necessary that only one user will write at a time. so is there any coding for this or? please help me out here i am stuck do not know what to do i have no practical experience, would appreciate all the help thank you

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  • How many users are sufficient to make a heavy load for web application

    - by galymzhan
    I have a web application, which has been suffering high load recent days. The application runs on single server which has 8-core Intel CPU and 4gb of RAM. Software: Drupal 5 (Apache 2, PHP5, MySQL5) running on Debian. After reaching 500 authenticated and 200 anonymous users (simultaneous), the application drastically decreases its performance up to total failure. The biggest load comes from authenticated users, who perform activities, causing insert/update/deletes on db. I think mysql is a bottleneck. Is it normal to slow down on such number of users? EDIT: I forgot to mention that I did some kind of profiling. I runned commands top, htop and they showed me that all memory was being used by MySQL! After some time MySQL starts to perform terribly slow, site goes down, and we have to restart/stop apache to reduce load. Administrators said that there was about 200 active mysql connections at that moment. The worst point is that we need to solve this ASAP, I can't do deep profiling analysis/code refactoring, so I'm considering 2 ways: my tables are MyIsam, I heard they use table-level locking which is very slow, is it right? could I change it to Innodb without worry? what if I take MySQL, and move it to dedicated machine with a lot of RAM?

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  • Generics vs inheritance (when no collection classes are involved)

    - by Ram
    This is an extension of this questionand probably might even be a duplicate of some other question(If so, please forgive me). I see from MSDN that generics are usually used with collections The most common use for generic classes is with collections like linked lists, hash tables, stacks, queues, trees and so on where operations such as adding and removing items from the collection are performed in much the same way regardless of the type of data being stored. The examples I have seen also validate the above statement. Can someone give a valid use of generics in a real-life scenario which does not involve any collections ? Pedantically, I was thinking about making an example which does not involve collections public class Animal<T> { public void Speak() { Console.WriteLine("I am an Animal and my type is " + typeof(T).ToString()); } public void Eat() { //Eat food } } public class Dog { public void WhoAmI() { Console.WriteLine(this.GetType().ToString()); } } and "An Animal of type Dog" will be Animal<Dog> magic = new Animal<Dog>(); It is entirely possible to have Dog getting inherited from Animal (Assuming a non-generic version of Animal)Dog:Animal Therefore Dog is an Animal Another example I was thinking was a BankAccount. It can be BankAccount<Checking>,BankAccount<Savings>. This can very well be Checking:BankAccount and Savings:BankAccount. Are there any best practices to determine if we should go with generics or with inheritance ?

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  • C# sqlite syntax in ASP.NET?

    - by acidzombie24
    -edit- This is no longer relevant and the question doesnt make sense to me anymore. I think i wanted to know how to create tables or know if the syntax is the same from winform to ASP.NET I am very use to sqlite http://sqlite.phxsoftware.com/ and would like to create a DB in a similar style. How do i do this? it doesnt need to be the same, just similar enough for me to enjoy. An example of the syntax. connection = new SQLiteConnection("Data Source=" + sz +";Version=3"); command = new SQLiteCommand(connection); connection.Open(); command.CommandText = "CREATE TABLE if not exists miscInfo(key TEXT, " + "value TEXT, UNIQUE (key));"; command.ExecuteNonQuery(); The @name is a symbol and command.Parameters.Add("@userDesc", DbType.String).Value = d.userDesc; replaces the symbol with escaped values/texts/blob command.CommandText = "INSERT INTO discData(rootfolderID, time, volumeName, discLabel, " + "userTitle, userDesc) "+ "VALUES(@rootfolderID, @time, @volumeName, @discLabel, " + "@userTitle, @userDesc); " + "SELECT last_insert_rowid() AS RecordID;"; command.Parameters.Add("@rootfolderID", DbType.Int64).Value = d.rootfolderID; command.Parameters.Add("@time", DbType.Int64).Value = d.time; command.Parameters.Add("@volumeName", DbType.String).Value = d.volumeName; command.Parameters.Add("@discLabel", DbType.String).Value = d.discLabel; command.Parameters.Add("@userTitle", DbType.String).Value = d.userTitle; command.Parameters.Add("@userDesc", DbType.String).Value = d.userDesc; d.discID = (long)command.ExecuteScalar();

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  • PostgreSQL: return select count(*) from old_ids;

    - by Alexander Farber
    Hello, please help me with 1 more PL/pgSQL question. I have a PHP-script run as daily cronjob and deleting old records from 1 main table and few further tables referencing its "id" column: create or replace function quincytrack_clean() returns integer as $BODY$ begin create temp table old_ids (id varchar(20)) on commit drop; insert into old_ids select id from quincytrack where age(QDATETIME) > interval '30 days'; delete from hide_id where id in (select id from old_ids); delete from related_mks where id in (select id from old_ids); delete from related_cl where id in (select id from old_ids); delete from related_comment where id in (select id from old_ids); delete from quincytrack where id in (select id from old_ids); return select count(*) from old_ids; end; $BODY$ language plpgsql; And here is how I call it from the PHP script: $sth = $pg->prepare('select quincytrack_clean()'); $sth->execute(); if ($row = $sth->fetch(PDO::FETCH_ASSOC)) printf("removed %u old rows\n", $row['count']); Why do I get the following error? SQLSTATE[42601]: Syntax error: 7 ERROR: syntax error at or near "select" at character 9 QUERY: SELECT select count(*) from old_ids CONTEXT: SQL statement in PL/PgSQL function "quincytrack_clean" near line 23 Thank you! Alex

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  • Django sub-applications & module structure

    - by Rob Golding
    I am developing a Django application, which is a large system that requires multiple sub-applications to keep things neat. Therefore, I have a top level directory that is a Django app (as it has an empty models.py file), and multiple subdirectories, which are also applications in themselves. The reason I have laid my application out in this way is because the sub-applications are separated, but they would never be used on their own, outside the parent application. It therefore makes no sense to distribute them separately. When installing my application, the settings file has to include something like this: INSTALLED_APPS = ( ... 'myapp', 'myapp.subapp1', 'myapp.subapp2', ... ) ...which is obviously suboptimal. This also has the slightly nasty result of requiring that all the sub-applications are referred to by their "inner" name (i.e. subapp1, subapp2 etc.). For example, if I want to reset the database tables for subapp1, I have to type: python manage.py reset subapp1 This is annoying, especially because I have a sub-app called core - which is likely to conflict with another application's name when my application is installed in a user's project. Am I doing this completely wrongly, or is there away to force these "inner" apps to be referred to by their full name?

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  • LINQ to SQL: Reusable expression for property?

    - by coenvdwel
    Pardon me for being unable to phrase the title more exact. Basically, I have three LINQ objects linked to tables. One is Product, the other is Company and the last is a mapping table Mapping to store what Company sells which products and by which ID this Company refers to this Product. I am now retrieving a list of products as follows: var options = new DataLoadOptions(); options.LoadWith<Product>(p => p.Mappings); context.LoadOptions = options; var products = ( from p in context.Products select new { ProductID = p.ProductID, //BackendProductID = p.BackendProductID, BackendProductID = (p.Mappings.Count == 0) ? "None" : (p.Mappings.Count > 1) ? "Multiple" : p.Mappings.First().BackendProductID, Description = p.Description } ).ToList(); This does a single query retrieving the information I want. But I want to be able to move the logic behind the BackendProductID into the LINQ object so I can use the commented line instead of the annoyingly nested ternary operator statements for neatness and re-usability. So I added the following property to the Product object: public string BackendProductID { get { if (Mappings.Count == 0) return "None"; if (Mappings.Count > 1) return "Multiple"; return Mappings.First().BackendProductID; } } The list is still the same, but it now does a query for every single Product to get it's BackendProductID. The code is neater and re-usable, but the performance now is terrible. What I need is some kind of Expression or Delegate but I couldn't get my head around writing one. It always ended up querying for every single product, still. Any help would be appreciated!

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  • SQL Databases and table design/organization

    - by John McMullen
    (NOOB disclaimer) I'm working on a system (a type of map), that is accessed mostly via 3 fields: ID (auto incremented), X coordinate, and Y coordinate. As it is right now, i have all data on the map, stored in 1 table. Whenever the map display is loaded it simply queries the database for contents in x and y, and the DB gives the data (other fields in the same entry). If an item on the map is doing something, it has a flag saying its doing something, and then has an ID of the action in another table holding that type of 'actions'. Essentially, for all map data, its stored in 1 table. All actions of a certain type are stored in their own table. I'm a noob, and i'm wondering what the most effective/efficient structure for such a design? (a map that has items, and each item has stats/actions). I'm using PHP atm, using standard SQL queries to get my data. Should i split up the tables so that there are only x number of entries on a table? (coord range limits)? Should it just keep growing and growing? There's a lot of queries to the table... so just tryin to see what is best :/

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  • How to use MySQL geospatial extensions with spherical geometries

    - by Joshua
    Hi Everyone, I would like to store thousands of latitude/longitude points in a MySQL db. I was successful at setting up the tables and adding the data using the geospatial extensions where the column 'coord' is a Point(lat, lng). Problem: I want to quickly find the 'N' closest entries to latitude 'X' degrees and longitude 'Y' degrees. Since the Distance() function has not yet been implemented, I used GLength() function to calculate the distance between (X,Y) and each of the entries, sorting by ascending distance, and limiting to 'N' results. The problem is that this is not calculating shortest distance with spherical geometry. Which means if Y = 179.9 degrees, the list of closest entries will only include longitudes of starting at 179.9 and decreasing even though closer entries exist with longitudes increasing from -179.9. How does one typically handle the discontinuity in longitude when working with spherical geometries in databases? There has to be an easy solution to this, but I must just be searching for the wrong thing because I have not found anything helpful. Should I just forget the GLength() function and create my own function for calculating angular separation? If I do this, will it still be fast and take advantage of the geospatial extensions? Thanks! josh UPDATE: This is exactly what I am describing above. However, it is only for SQL Server. Apparently SQL Server has a Geometry and Geography datatypes. The geography does exactly what I need. Is there something similar in MySQL?

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  • How to track auto-generated id's in select-insert statement

    - by k rey
    I have two tables detail and head. The detail table will be written first. Later, the head table will be written. The head is a summary of the detail table. I would like to keep a reference from the detail to the head table. I have a solution but it is not elegant and requires duplicating the joins and filters that were used during summation. I am looking for a better solution. The below is an example of what I currently have. In this example, I have simplified the table structure. In the real world, the summation is very complex. -- Preparation create table #detail ( detail_id int identity(1,1) , code char(4) , amount money , head_id int null ); create table #head ( head_id int identity(1,1) , code char(4) , subtotal money ); insert into #detail ( code, amount ) values ( 'A', 5 ); insert into #detail ( code, amount ) values ( 'A', 5 ); insert into #detail ( code, amount ) values ( 'B', 2 ); insert into #detail ( code, amount ) values ( 'B', 2 ); -- I would like to somehow simplify the following two queries insert into #head ( code, subtotal ) select code, sum(amount) from #detail group by code update #detail set head_id = h.head_id from #detail d inner join #head h on d.code = h.code -- This is the desired end result select * from #detail Desired end result of detail table: detail_id code amount head_id 1 A 5.00 1 2 A 5.00 1 3 B 2.00 2 4 B 2.00 2

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  • Can I force the auto-generated Linq-to-SQL classes to use an OUTER JOIN?

    - by Gary McGill
    Let's say I have an Order table which has a FirstSalesPersonId field and a SecondSalesPersonId field. Both of these are foreign keys that reference the SalesPerson table. For any given order, either one or two salespersons may be credited with the order. In other words, FirstSalesPersonId can never be NULL, but SecondSalesPersonId can be NULL. When I drop my Order and SalesPerson tables onto the "Linq to SQL Classes" design surface, the class builder spots the two FK relationships from the Order table to the SalesPerson table, and so the generated Order class has a SalesPerson field and a SalesPerson1 field (which I can rename to SalesPerson1 and SalesPerson2 to avoid confusion). Because I always want to have the salesperson data available whenever I process an order, I am using DataLoadOptions.LoadWith to specify that the two salesperson fields are populated when the order instance is populated, as follows: dataLoadOptions.LoadWith<Order>(o => o.SalesPerson1); dataLoadOptions.LoadWith<Order>(o => o.SalesPerson2); The problem I'm having is that Linq to SQL is using something like the following SQL to load an order: SELECT ... FROM Order O INNER JOIN SalesPerson SP1 ON SP1.salesPersonId = O.firstSalesPersonId INNER JOIN SalesPerson SP2 ON SP2.salesPersonId = O.secondSalesPersonId This would make sense if there were always two salesperson records, but because there is sometimes no second salesperson (secondSalesPersonId is NULL), the INNER JOIN causes the query to return no records in that case. What I effectively want here is to change the second INNER JOIN into a LEFT OUTER JOIN. Is there a way to do that through the UI for the class generator? If not, how else can I achieve this? (Note that because I'm using the generated classes almost exclusively, I'd rather not have something tacked on the side for this one case if I can avoid it).

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  • Trouble creating a SQL query

    - by JoBu1324
    I've been thinking about how to compose this SQL query for a while now, but after thinking about it for a few hours I thought I'd ask the SO community to see if they have any ideas. Here is a mock up of the relevant portion of the tables: contracts id date ar (yes/no) term payments contract_id payment_date The object of the query is to determine, per month, how many payments we expect, vs how many payments we received. conditions for expecting a payment Expected payments begin on contracts.term months after contracts.date, if contracts.ar is "yes". Payments continue to be expected until the month after the first missed payment. There is one other complication to this: payments might be late, but they need to show up as if they were paid on the date expected. The data is all there, but I've been having trouble wrapping my head around the SQL query. I am not an SQL guru - I merely have a decent amount of experience handling simpler queries. I'd like to avoid filtering the results in code, if possible - but without your help that may be what I have to do. Expected Output Month Expected Payments Received Payments January 500 450 February 498 478 March 234 211 April 987 789 ... SQL Fiddle I've created an SQL Fiddle: http://sqlfiddle.com/#!2/a2c3f/2

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  • Can I use foreign key restrictions to return meaningful UI errors with PHP

    - by Shane
    I want to start by saying that I am a big fan of using foreign keys and have a tendency to use them even on small projects to keep my database from being filled with orphaned data. On larger projects I end up with gobs of keys which end up covering upwards of 8 - 10 layers of data. I want to know if anyone could suggest a graceful way of handling 'expected errors' from the MySQL database in a way that I can construct meaningful messages for the end user. I will explain 'expected errors' with an example. Lets say I have a set of tables used for basic discussions: discussion questions responses users Hierarchically they would probably look something like this: -users --discussion ---questions ----responses When I attempt to delete a user the FKs will check discussions and if any discussion exist the deletion is restricted, deleting discussion checks questions, deleting questions checks responses. An 'expected error' in this case would be attempting to delete a user--unless they are newly created I can anticipate that one or more foreign keys will fail causing an error. What I WANT to do is to catch that error on deletion and be able to tell the end user something like 'We're sorry, but all discussions must be removed before you can delete this user...'. Now I know I can keep and maintain matching arrays in PHP and map specific errors to messages but that is messy and prone to becoming stagnant, or I could manually run a set of selects prior to attempting the deletion, but then I am doing just as much work as without using FKs. Any help here would be greatly appreciated, or if I am just looking at this completely wrong then please let me know. On a side note I generally use CodeIgniter for my application development, so if that would open up an avenue through that framework please consider that in your answers. Thanks in Advance

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  • Populating and Using Dynamic Classes in C#/.NET 4.0

    - by Bob
    In our application we're considering using dynamically generated classes to hold a lot of our data. The reason for doing this is that we have customers with tables that have different structures. So you could have a customer table called "DOG" (just making this up) that contains the columns "DOGID", "DOGNAME", "DOGTYPE", etc. Customer #2 could have the same table "DOG" with the columns "DOGID", "DOG_FIRST_NAME", "DOG_LAST_NAME", "DOG_BREED", and so on. We can't create classes for these at compile time as the customer can change the table schema at any time. At the moment I have code that can generate a "DOG" class at run-time using reflection. What I'm trying to figure out is how to populate this class from a DataTable (or some other .NET mechanism) without extreme performance penalties. We have one table that contains ~20 columns and ~50k rows. Doing a foreach over all of the rows and columns to create the collection take about 1 minute, which is a little too long. Am I trying to come up with a solution that's too complex or am I on the right track? Has anyone else experienced a problem like this? Create dynamic classes was the solution that a developer at Microsoft proposed. If we can just populate this collection and use it efficiently I think it could work.

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  • Need help with many-to-many relationships....

    - by yuudachi
    I have a student and faculty table. The primary key for student is studendID (SID) and faculty's primary key is facultyID, naturally. Student has an advisor column and a requested advisor column, which are foreign key to faculty. That's simple enough, right? However, now I have to throw in dates. I want to be able to view who their advisor was for a certain quarter (such as 2009 Winter) and who they had requested. The result will be a table like this: Year | Term | SID | Current | Requested ------------------------------------------------ 2009 | Winter | 860123456 | 1 | NULL 2009 | Winter | 860445566 | 3 | NULL 2009 | Winter | 860369147 | 5 | 1 And then if I feel like it, I could also go ahead and view a different year and a different term. I am not sure how these new table(s) will look like. Will there be a year table with three columns that are Fall, Spring and Winter? And what will the Fall, Spring, Winter table have? I am new to the art of tables, so this is baffling me... Also, I feel I should clarify how the site works so far now. Admin can approve student requests, and what happens is that the student's current advisor gets overwritten with their request. However, I think I should not do that anymore, right?

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  • Problem importing Oracle .dmp file

    - by BitFiddler
    So I have looked at all the suggested ways of importing .dmp files and non of them seem to answer this question: where does the data go once you import it? Context: I created a user like so: SQL> create user IMPORTER identified by "12345"; SQL> grant connect, unlimited tablespace, resource to IMPORTER; I then ran the 'imp' command as follows: C:\>imp system/password FROMUSER=OVIEDOE TOUSER=IMPORTER file=c:\database1.dmp Now there were 9 .dmp files, after each one it asked me for the next one and then I received the message "Import terminated successfully with warnings." The warning was: Warning: the objects were exported by OVIEDOE, not by you import done in WE8MSWIN1252 character set and AL16UTF16 NCHAR character set export client uses WE8ISO8859P1 character set (possible charset conversion) IMP-00046: using FILESIZE value from export file of 2147483648 Now it says it was terminated successfully so my assumption (I am new to oracle so this may be wrong) is that the data was loaded. However, when I use SQL developer to connect to the database and look under the 'tables' node under the IMPORTER user, there is nothing there. What is going on? Did the data load? If so, where can I find it?

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  • A typical mysql query( how to use subquery column into main query)

    - by I Like PHP
    I HAVE TWO TABLES shown below table_joining id join_id(PK) transfer_id(FK) unit_id transfer_date joining_date 1 j_1 t_1 u_1 2010-06-05 2010-03-05 2 j_2 t_2 u_3 2010-05-10 2010-03-10 3 j_3 t_3 u_6 2010-04-10 2010-01-01 4 j_5 NULL u_3 NULL 2010-06-05 5 j_6 NULL u_4 NULL 2010-05-05 table_transfer id transfer_id(PK) pastUnitId futureUnitId effective_transfer_date 1 t_1 u_3 u_1 2010-06-05 2 t_2 u_6 u_1 2010-05-10 3 t_3 u_5 u_3 2010-04-10 now i want to know total employee detalis( using join_id) which are currently working on unit u_3 . means i want only join_id j_1 (has transfered but effective_transfer_date is future date, right now in u_3) j_2 ( tansfered and right now in `u_3` bcoz effective_transfer_date has been passed) j_6 ( right now in `u_3` and never transfered) what i need to take care of below steps( as far as i know ) <1> first need to check from table_joining whether transfer_id is NULL or not <2> if transfer_id= is NULL then see unit_id=u_3 where joining_date <=CURDATE() ( means that person already joined u_3) <3> if transfer_id is NOT NULL then go to table_transfer using transfer_id (foreign key reference) <4> now see the effective_transfer_date regrading that transfer_id whether effective_transfer_date<=CURDATE() <5> if transfer date has been passed(means transfer has been done) then return futureUnitID otherwise return pastUnitID i used two separate query but don't know how to join those query?? for step <1 ans <2 SELECT unit_id FROM table_joining WHERE joining_date<=CURDATE() AND transfer_id IS NULL AND unit_id='u_3' for step<5 SELECT IF(effective_transfer_date <= CURDATE(),futureUnitId,pastUnitId) AS currentUnitID FROM table_transfer // here how do we select only those rows which have currentUnitID='u_3' ?? please guide me the process?? i m just confused with JOINS. i think using LEFT JOIN can return the data i need, or if we use subquery value to main query? but i m not getting how to implement ...please help me. Thanks for helping me alwayz

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