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  • Self-referencing tables in Linq2Sql

    - by J-Man
    Hi, I've seen a lot of questions on self-referencing tables in Linq2Sql and how to eagerly load all child records for a particular root object. I've implemented a temporary solution by accessing all underlying properties, but you can see that this doesn't do the performance any good. The thing is though, that all records are correlated with each-other using a correlation GUID. Example below: RootElement - Id: 1 - ParentId: null - CorrelationId: 4D68E512-4B55-44f4-BA5A-174B630A03DD ChildElement1 - Id: 2 - ParentId: 1 - CorrelationId: 4D68E512-4B55-44f4-BA5A-174B630A03DD ChildElement2 - Id: 3 - ParentId: 2 - CorrelationId: 4D68E512-4B55-44f4-BA5A-174B630A03DD ChildElement1 - Id: 4 - ParentId: 2 - CorrelationId: 4D68E512-4B55-44f4-BA5A-174B630A03DD In my case, I do have access to the correlationId, so I can retrieve all of my records by performing the following query: from element in db.Elements where element.CorrelationId == '4D68E512-4B55-44f4-BA5A-174B630A03DD' select element; But, of course, I want these elements associated with each other by executing this query: from element in db.Elements where element.CorrelationId == '4D68E512-4B55-44f4-BA5A-174B630A03DD' && element.ParentId == null select element; My question is: is it possible to combine the results the first query as some sort of 'caching mechanism' for the query where I get the root element? Thanks for the input. J.

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  • Nullable Integer ? (working with linq)

    - by nCdy
    I've got exception about convert NULL to Int32. I've got a table from database with nullable tinyint [Column(Storage="_StatType", DbType="tinyint NULL")] public StatType : int { get { _StatType; } } (to get C# code just replace variable's type) and after making linq select def StartLinq = linq <#from lpi in _CfgListParIzm where lpi.ID_ListParIzm==drr1 select (lpi.StatType) #> ; StartLinq.ToArray()[0] can't be readed if that is null :-/ mutable STT : int = 0; try { _=int.TryParse(StartLinq.ToArray()[0].ToString(), out STT); } catch { | _ is Exception => () /* I don't care*/ } upper code is very poor trick :( I wont use it.

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  • Help to choose NoSQL database for project

    - by potapuff
    There is a table: doc_id(integer)-value(integer) Approximate 100k doc_id and 27?? rows. Majority query on this table - searching documents similar to current document: select 10 documents with maximum of (count common to current document value)/(count ov values in document). Nowadays we use PostgreSQL. Table weight (with index) ~1,5 GB. Average query time ~0.5s. Should I transfer all this to NoSQL base, if so, what?

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  • Best solution for a comment table for multiple content types

    - by KRTac
    I'm currently designing a comments table for a site I'm building. Users will be able to upload images, link videos and add audio files to the profile. Each of these types of content must be commentable. Now I'm wondering what's the best approach to this. My current options are: 1. to have one big comments table and a link tables for every content type (comments_videos, ...) with comment_id and _id. 2. to have comments separated by the type of content their for. So each type of content would have his own comments table with the comments for that type.

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  • Why index_merge is not used here?

    - by user198729
    Setup: mysql> create table t(a integer unsigned,b integer unsigned); mysql> insert into t(a,b) values (1,2),(1,3),(2,4); mysql> create index i_t_a on t(a); mysql> create index i_t_b on t(b); mysql> explain select * from t where a=1 or b=4; +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | 1 | SIMPLE | t | ALL | i_t_a,i_t_b | NULL | NULL | NULL | 3 | Using where | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ Is there something I'm missing?

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  • Stored Procedures last access time?

    - by Ardman
    Is it possible to find out when a Stored Procedure was last accessed? I tried the following: SELECT * FROM sys.dm_db_index_usage_stats WHERE [database_id] = DB_ID() AND [object_id] = OBJECT_ID('stored procedure name') and it returns a blank resultset.

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  • I need some help optimizing my database schema

    - by Steffan
    Here's a layout of my data: Heading 1: Sub heading Sub heading Sub heading Sub heading Sub heading Heading 2: Sub heading Sub heading Sub heading Sub heading Sub heading Heading 3: Sub heading Sub heading Sub heading Sub heading Sub heading Heading 4: Sub heading Sub heading Sub heading Sub heading Sub heading Heading 5: Sub heading Sub heading Sub heading Sub heading Sub heading These headings need to have a 'Completion Status' boolean value which gets linked to a user Id. Currently, this is how my table looks: id | userID | field_1 | field_2 | field_3 | field_4 | etc... ----------------------------------------------------------------------- 1 | 1 | 0 | 0 | 1 | 0 | ----------------------------------------------------------------------- 2 | 2 | 1 | 0 | 1 | 1 | Each field represents one Sub Heading. Having this many columns in my table looks awfully inefficient... How can I go about optimizing this? I can't think of any way to neaten it up :/

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  • Historical / auditable database

    - by Mark
    Hi all, This question is related to the schema that can be found in one of my other questions here. Basically in my database I store users, locations, sensors amongst other things. All of these things are editable in the system by users, and deletable. However - when an item is edited or deleted I need to store the old data; I need to be able to see what the data was before the change. There are also non-editable items in the database, such as "readings". They are more of a log really. Readings are logged against sensors, because its the reading for a particular sensor. If I generate a report of readings, I need to be able to see what the attributes for a location or sensor was at the time of the reading. Basically I should be able to reconstruct the data for any point in time. Now, I've done this before and got it working well by adding the following columns to each editable table: valid_from valid_to edited_by If valid_to = 9999-12-31 23:59:59 then that's the current record. If valid_to equals valid_from, then the record is deleted. However, I was never happy with the triggers I needed to use to enforce foreign key consistency. I can possibly avoid triggers by using the extension to the "PostgreSQL" database. This provides a column type called "period" which allows you to store a period of time between two dates, and then allows you to do CHECK constraints to prevent overlapping periods. That might be an answer. I am wondering though if there is another way. I've seen people mention using special historical tables, but I don't really like the thought of maintainling 2 tables for almost every 1 table (though it still might be a possibility). Maybe I could cut down my initial implementation to not bother checking the consistency of records that aren't "current" - i.e. only bother to check constraints on records where the valid_to is 9999-12-31 23:59:59. Afterall, the people who use historical tables do not seem to have constraint checks on those tables (for the same reason, you'd need triggers). Does anyone have any thoughts about this? PS - the title also mentions auditable database. In the previous system I mentioned, there is always the edited_by field. This allowed all changes to be tracked so we could always see who changed a record. Not sure how much difference that might make. Thanks.

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  • Revert scan state when prompting for variable values

    - by Dave Jarvis
    How do you detect the current SCAN state and revert it after changing it? An exerpt from the script in question: SET SCAN OFF SET ECHO ON SET SQLBLANKLINES ON SET SCAN ON UPDATE TABLE_NAME SET CREATED_BY = &&created_by; SET SCAN OFF The problem is that if the script doesn't have the first line (SET SCAN OFF), then the code to prompt the user should not turn the SCAN state off. In pseudocode, we'd like to do the following: SET SCAN OFF SET ECHO ON SET SQLBLANKLINES ON PUSH SCAN STATE SET SCAN ON UPDATE TABLE_NAME SET CREATED_BY = &&created_by; POP SCAN STATE The psudeocode PUSH SCAN STATE remembers the state so that if the code is altered by removing the first line, the rest of the script still works as expected.

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  • How can we secure our data from DBA?

    - by KoolKabin
    Hi guys, I have very confidential data in my database. I am trying to secure my data from dba. I am a member of development team. We develop our software and delpoy in a server which has its own dba. We have limited control over the server. In this scenario how can i deny dba of the server to lookup my data and deny making changes to them. Is it possible?

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  • Applying Domain Model on top of Linq2Sql entities

    - by Thomas
    I am trying to practice the model first approach and I am putting together a domain model. My requirement is pretty simple: UserSession can have multiple ShoppingCartItems. I should start off by saying that I am going to apply the domain model interfaces to Linq2Sql generated entities (using partial classes). My requirement translates into three database tables (UserSession, Product, ShoppingCartItem where ProductId and UserSessionId are foreign keys in the ShoppingCartItem table). Linq2Sql generates these entities for me. I know I shouldn't even be dealing with the database at this point but I think it is important to mention. The aggregate root is UserSession as a ShoppingCartItem can not exist without a UserSession but I am unclear on the rest. What about Product? It is defiently an entity but should it be associated to ShoppingCartItem? Here are a few suggestion (they might all be incorrect implementations): public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItem> ShoppingCartItems{ get; set; } } public interface IShoppingCartItem { public Guid UserSessionId { get; set; } public int ProductId { get; set; } } Another one would be: public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItem> ShoppingCartItems{ get; set; } } public interface IShoppingCartItem { public Guid UserSessionId { get; set; } public IProduct Product { get; set; } } A third one is: public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItemColletion> ShoppingCartItems{ get; set; } } public interface IShoppingCartItemColletion { public IUserSession UserSession { get; set; } public IProduct Product { get; set; } } public interface IProduct { public int ProductId { get; set; } } I have a feeling my mind is too tightly coupled with database models and tables which is making this hard to grasp. Anyone care to decouple?

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  • PLPGSQL : How to return a record from function executed by INSERT/UPDATE rule?

    - by seas
    Do the following scheme for my database: create sequence data_sequence; create table data_table { id integer primary key; field varchar(100); }; create view data_view as select id, field from data_table; create function data_insert(_new data_view) returns data_view as $$declare _id integer; _result data_view%rowtype; begin _id := nextval('data_sequence'); insert into data_table(id, field) values(_id, _new.field); select * into _result from data_view where id = _id; return _result; end; $$ language plpgsql; create rule insert as on insert to data_view do instead select data_insert(new); Then type in psql: insert into data_view(field) values('abc'); Would like to see something like: id | field ----+--------- 1 | abc Instead see: data_insert ------------- (1, "abc") Is it possible to fix this somehow? Thanks for any ideas. Ultimate idea is to use this in other functions, so that I could obtain id of just inserted record without selecting for it from scratch. Something like: insert into data_view(field) values('abc') returning id into my_variable would be nice but doesn't work with error: ERROR: cannot perform INSERT RETURNING on relation "data_view" HINT: You need an unconditional ON INSERT DO INSTEAD rule with a RETURNING clause. I don't really understand that HINT. I use PostgreSQL 8.4.

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  • Representing Sparse Data in PostgreSQL

    - by Chris S
    What's the best way to represent a sparse data matrix in PostgreSQL? The two obvious methods I see are: Store data in a single a table with a separate column for every conceivable feature (potentially millions), but with a default value of NULL for unused features. This is conceptually very simple, but I know that with most RDMS implementations, that this is typically very inefficient, since the NULL values ususually takes up some space. However, I read an article (can't find its link unfortunately) that claimed PG doesn't take up data for NULL values, making it better suited for storing sparse data. Create separate "row" and "column" tables, as well as an intermediate table to link them and store the value for the column at that row. I believe this is the more traditional RDMS solution, but there's more complexity and overhead associated with it. I also found PostgreDynamic, which claims to better support sparse data, but I don't want to switch my entire database server to a PG fork just for this feature. Are there any other solutions? Which one should I use?

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  • Date arithmetic using integer values

    - by Dave Jarvis
    Problem String concatenation is slowing down a query: date(extract(YEAR FROM m.taken)||'-1-1') d1, date(extract(YEAR FROM m.taken)||'-1-31') d2 This is realized in code as part of a string, which follows (where the p_ variables are integers): date(extract(YEAR FROM m.taken)||''-'||p_month1||'-'||p_day1||''') d1, date(extract(YEAR FROM m.taken)||''-'||p_month2||'-'||p_day2||''') d2 This part of the query runs in 3.2 seconds with the dates, and 1.5 seconds without, leading me to believe there is ample room for improvement. Question What is a better way to create the date (presumably without concatenation)? Many thanks!

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  • Problem with interface implementation in partial classes.

    - by Bas
    I have a question regarding a problem with L2S, Autogenerated DataContext and the use of Partial Classes. I have abstracted my datacontext and for every table I use, I'm implementing a class with an interface. In the code below you can see I have the Interface and two partial classes. The first class is just there to make sure the class in the auto-generated datacontext inherets Interface. The other autogenerated class makes sure the method from Interface is implemented. namespace PartialProject.objects { public interface Interface { Interface Instance { get; } } //To make sure the autogenerated code inherits Interface public partial class Class : Interface { } //This is autogenerated public partial class Class { public Class Instance { get { return this.Instance; } } } } Now my problem is that the method implemented in the autogenerated class gives the following error: - Property 'Instance' cannot implement property from interface 'PartialProject.objects.Interface'. Type should be 'PartialProjects.objects.Interface'. <- Any idea how this error can be resolved? Keep in mind that I can't edit anything in the autogenerated code. Thanks in advance!

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  • Using outer query result in a subquery in postgresql

    - by brad
    I have two tables points and contacts and I'm trying to get the average points.score per contact grouped on a monthly basis. Note that points and contacts aren't related, I just want the sum of points created in a month divided by the number of contacts that existed in that month. So, I need to sum points grouped by the created_at month, and I need to take the count of contacts FOR THAT MONTH ONLY. It's that last part that's tricking me up. I'm not sure how I can use a column from an outer query in the subquery. I tried something like this: SELECT SUM(score) AS points_sum, EXTRACT(month FROM created_at) AS month, date_trunc('MONTH', created_at) + INTERVAL '1 month' AS next_month, (SELECT COUNT(id) FROM contacts WHERE contacts.created_at <= next_month) as contact_count FROM points GROUP BY month, next_month ORDER BY month So, I'm extracting the actual month that my points are being summed, and at the same time, getting the beginning of the next_month so that I can say "Get me the count of contacts where their created at is < next_month" But it complains that column next_month doesn't exist This is understandable as the subquery knows nothing about the outer query. Qualifying with points.next_month doesn't work either. So can someone point me in the right direction of how to achieve this? Tables: Points score | created_at 10 | "2011-11-15 21:44:00.363423" 11 | "2011-10-15 21:44:00.69667" 12 | "2011-09-15 21:44:00.773289" 13 | "2011-08-15 21:44:00.848838" 14 | "2011-07-15 21:44:00.924152" Contacts id | created_at 6 | "2011-07-15 21:43:17.534777" 5 | "2011-08-15 21:43:17.520828" 4 | "2011-09-15 21:43:17.506452" 3 | "2011-10-15 21:43:17.491848" 1 | "2011-11-15 21:42:54.759225" sum, month and next_month (without the subselect) sum | month | next_month 14 | 7 | "2011-08-01 00:00:00" 13 | 8 | "2011-09-01 00:00:00" 12 | 9 | "2011-10-01 00:00:00" 11 | 10 | "2011-11-01 00:00:00" 10 | 11 | "2011-12-01 00:00:00"

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  • Replace duplicate spaces with single space in TSQL

    - by Chris
    I need to ensure that a given field does not have more than one space (not concerned about all white space, just space) between characters. So 'single spaces only' Needs to turn into 'single spaces only' The below will not work select replace('single spaces only',' ',' ') as it would result in 'single spaces only' I would really prefer to stick with native TSQL rather than a CLR based solution. Thoughts?

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  • MySQL Select problems

    - by John Nuñez
    Table #1: qa_returns_items Table #2: qa_returns_residues I have a long time trying to get this Result: item_code - item_quantity 2 - 1 3 - 2 IF qa_returns_items.item_code = qa_returns_residues.item_code AND status_code = 11 THEN item_quantity = qa_returns_items.item_quantity - qa_returns_residues.item_quantity ELSEIF qa_returns_items.item_code = qa_returns_residues.item_code AND status_code = 12 THEN item_quantity = qa_returns_items.item_quantity + qa_returns_residues.item_quantity ELSE show diferendes END IF I tried this Query: select SubQueryAlias.item_code, total_ecuation, SubQueryAlias.item_unitprice, SubQueryAlias.item_unitprice * total_ecuation as item_subtotal, item_discount, (SubQueryAlias.item_unitprice * total_ecuation) - item_discount as item_total from ( select ri.item_code , case status_code when 11 then ri.item_quantity - rr.item_quantity when 12 then ri.item_quantity + rr.item_quantity end as total_ecuation , rr.item_unitprice , rr.item_quantity , rr.item_discount * rr.item_quantity as item_discount from qa_returns_residues rr left join qa_returns_items ri on ri.item_code = rr.item_code WHERE ri.returnlog_code = 1 ) as SubQueryAlias where total_ecuation > 0 GROUP BY (item_code); The query returns this result: item_code - item_quantity 1 - 2 2 - 2

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  • SSIS(sql server integration service) xml data flow

    - by swapna
    Hi, I have an xml file the content which i have to write to a Database table using ssis pacakge. I am using xml source nad oledb destination My issue now is this xml file generate multiple outputs .(event,produt,offer,form) etc. But i need to write all in one data row(more than one if 2 products are there for the event) in the database. But i do not know how to use this multiple outputs and make a single row for a event. I hav read numerous articles about this subject but not able to take a decision.what is the right way of doing this. 1) xml source ? (if i use this how do i merge the multiple outputs) 2) or a script task using xml objects read and write to the DB. or anything new ? Please provide me some solutions xml sample file * - ABc. 2009-06-07 2010-04-30 region test 1 contact - offertest product1 product1 187 * Thanks SNA

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  • .NET and Closing MSSQL connections

    - by user307076
    I am having a hard time figuring out why the following constructor will not close connnections. When I view the active connections. Here is the code that I have. Public Sub New(ByVal UserID As Integer) Dim oConn As New SqlConnection(ConfigurationManager.ConnectionStrings("connStr").ToString()) Dim cmd As New SqlCommand("stored proc", oConn) Dim sdr As SqlDataReader cmd.CommandType = CommandType.StoredProcedure cmd.Parameters.AddWithValue("@userID", UserID) oConn.Open() sdr = cmd.ExecuteReader() Try If Not sdr.HasRows Then sdr.Close() If Not oConn Is Nothing Then If oConn.State <> ConnectionState.Closed Then oConn.Close() End If End If cmd.Dispose() Exit Sub End If 'User has account in WATS, proceed to load account information While sdr.Read _firstname = Convert.ToString(sdr("First Name")) _lastname = Convert.ToString(sdr("Last Name")) End While Catch ex As Exception 'Throw New Exception("User Error: " + ex.Message) Finally sdr.Close() If Not oConn Is Nothing Then If oConn.State <> ConnectionState.Closed Then oConn.Close() End If End If cmd.Dispose() End Try End Sub

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  • Wiki Database, is there one?

    - by Faiz
    I was searching the net for something like a wiki database, just like wikipedia but instead stores structured content, editable by users. What I was looking for was an online database accessible by everyone where people can design the schema and data with proper versioning of both schema and data. I couldn't find any such site. I am not sure if it is my search skills or if there really is no wiki database as of now. Does anyone out there know anything like this? I think there is a great potential for something like this. A possible example will be a website with a GUI for querying a MySQL DB where any website visitor can create DB objects and populate data.

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  • How does Select statement works in a Dynamic Linq Query?

    - by Richard77
    Hello, 1) I've a Product table with 4 columns: ProductID, Name, Category, and Price. Here's the regular linq to query this table. public ActionResult Index() { private ProductDataContext db = new ProductDataContext(); var products = from p in db.Products where p.Category == "Soccer" select new ProductInfo { Name = p.Name, Price = p.Price} return View(products); } Where ProductInfo is just a class that contains 2 properties (Name and Price). The Index page Inherits ViewPage - IEnumerable - ProductInfo. Everything works fine. 2) To dynamicaly execute the above query, I do this: Public ActionResult Index() { var products = db.Products .Where("Category = \"Soccer\"") .Select(/* WHAT SOULD I WRITE HERE TO SELECT NAME & PRICE?*/) return View(products); } I'm using both 'System.Lind.Dynamic' namespace and the DynamicLibrary.cs (downloaded from ScottGu blog). Here are my questions: What expression do I use to select only Name and Price? (Most importantly) How do I retrieve the data in my view? (i.e. What type the ViewPage inherits? ProductInfo?)

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