Search Results

Search found 21589 results on 864 pages for 'primary key'.

Page 300/864 | < Previous Page | 296 297 298 299 300 301 302 303 304 305 306 307  | Next Page >

• Building a many-to-many db schema using only an unpredictable number of foreign keys

  - by user1449855

  Good afternoon (at least around here), I have a many-to-many relationship schema that I'm having trouble building. The main problem is that I'm only working with primary and foreign keys (no varchars or enums to simplify things) and the number of many-to-many relationships is not predictable and can increase at any time. I looked around at various questions and couldn't find something that directly addressed this issue. I split the problem in half, so I now have two one-to-many schemas. One is solved but the other is giving me fits. Let's assume table FOO is a standard, boring table that has a simple primary key. It's the one in the one-to-many relationship. Table BAR can relate to multiple keys of FOO. The number of related keys is not known beforehand. An example: From a query FOO returns ids 3, 4, 5. BAR needs a unique key that relates to 3, 4, 5 (though there could be any number of ids returned) The usual join table does not work: Table FOO_BAR primary_key | foo_id | bar_id | Since FOO returns 3 unique keys and here bar_id has a one-to-one relationship with foo_id. Having two join tables does not seem to work either, as it still can't map foo_ids 3, 4, 5 to a single bar_id. Table FOO_TO_BAR primary_key | foo_id | bar_to_foo_id | Table BAR_TO_FOO primary_key | foo_to_bar_id | bar_id | What am I doing wrong? Am I making things more complicated than they are? How should I approach the problem? Thanks a lot for the help.

  Read the article

• implementing twitter bootstrap carousel

  - by arboles

  I am having trouble implementing the bootstrap carousel. Can anyone look at the following html and js and give me instructions on how to implement the slide. The .js has not been edited and the carousel is installed on the body hero unit. Do I implement the carousel api? How do I define the carousel I am using within the .js file? Thanks. <div class="carousel"> <!-- Carousel items --> <div class="carousel-inner"> <!-- Main hero unit for a primary marketing message or call to action --> <div class="hero-unit"> <h1>Hello, world!</h1> <p>This is a template for a simple marketing or informational website. It includes a large callout called the hero unit and three supporting pieces of content. Use it as a starting point to create something more unique.</p> <p><a class="btn btn-primary btn-large">Learn more &raquo;</a></p> </div> </div> <!-- Carousel nav --> <a class="carousel-control left" href="#myCarousel" data-slide="prev">&lsaquo;</a> <a class="carousel-control right" href="#myCarousel" data-slide="next">&rsaquo;</a> </div>

  Read the article

• How do I create and use a junction table in Rails?

  - by Thierry Lam

  I have the following data: A post called Hello has categories greet Another post called Hola has categories greet, international My schema is: create_table "posts", :force => true do |t| t.string "name" t.datetime "created_at" t.datetime "updated_at" end create_table "categories", :force => true do |t| t.string "name" t.datetime "created_at" t.datetime "updated_at" end create_table "posts_categories", :force => true do |t| t.integer "post_id" t.integer "category_id" t.datetime "created_at" t.datetime "updated_at" end After reading the Rails guide, the most suitable relationship for the above seems to be: class Post < ActiveRecord::Base has_and_belongs_to_many :categories end class Category < ActiveRecord::Base has_and_belongs_to_many :posts end My junction table also seems to have a primary key. I think I need to get rid of it. What's the initial migration command to generate a junction table in Rails? What's the best course of action, should I drop posts_categories and re-create it or just drop the primary key column? Does the junction table have a corresponding model? I have used scaffold to generate the junction table code, should I get rid of the extra code? Assuming all the above has been fixed and is working properly, how do I query all posts and display them along with their named categories in the view. For example: Post #1 - hello, categories: greet Post #2 - hola, categories: greet, international

  Read the article

• SQL GUID Vs Integer

  - by Dal

  Hi I have recently started a new job and noticed that all the SQL tables use the GUID data type for the primary key. In my previous job we used integers (Auto-Increment) for the primary key and it was a lot more easier to work with in my opinion. For example, say you had two related tables; Product and ProductType - I could easily cross check the 'ProductTypeID' column of both tables for a particular row to quickly map the data in my head because its easy to store the number (2,4,45 etc) as opposed to (E75B92A3-3299-4407-A913-C5CA196B3CAB). The extra frustration comes from me wanting to understand how the tables are related, sadly there is no Database diagram :( A lot of people say that GUID's are better because you can define the unique identifer in your C# code for example using NewID() without requiring SQL SERVER to do it - this also allows you to know provisionally what the ID will be.... but I've seen that it is possible to still retrieve the 'next auto-incremented integer' too. A DBA contractor reported that our queries could be up to 30% faster if we used the Integer type instead of GUIDS... Why does the GUID data type exist, what advantages does it really provide?... Even if its a choice by some professional there must be some good reasons as to why its implemented?

  Read the article

• WordPerfect programmers refusing to use anything but assembler

  - by Totophil

  There is a version (popularised by Joel Spolsky) attributing the demise of WordPerfect to a refusal of its programmers to use anything but assembler that led to delay of the first WPwin release and as result eventually to losing the all important battle with Microsoft. There are a few references to programming work being done using assembler in the autobiographical book "Almost Perfect" by W. E. Pete Peterson who used to have a major influence at running the corporation. But these references go back to early 80's when WordPerfect was trying to gain a significant market share by defeating WordStar and not early nineties when the battle with MS took place. I am looking for a second independent source to confirm the assumption. Maybe someone who worked for WordPerfect Corporation at a time, who was close to the company, or had a chance to see the source could clarify the issue. Your help is much appreciated, thanks! Please note that this question is not about any other theories or reasons behind WordPerfect demise. I really just need to clarify whether they used assembler as a primary language for WPwin and (as a bonus really) whether there were discussions held within the corporation about assembler being the right choice. Concisely: Did WPCorp use assembler as a primary language for WPwin? Were discussions held at a time amongst WP Corp staff about assembler being the right choice (was it management or programmers decision)?

  Read the article

• Mapping composite foreign keys in a many-many relationship in Entity Framework

  - by Kirk Broadhurst

  I have a Page table and a View table. There is a many-many relationship between these two via a PageView table. Unfortunately all of these tables need to have composite keys (for business reasons). Page has a primary key of (PageCode, Version), View has a primary key of (ViewCode, Version). PageView obviously enough has PageCode, ViewCode, and Version. The FK to Page is (PageCode, Version) and the FK to View is (ViewCode, Version) Makes sense and works, but when I try to map this in Entity framework I get Error 3021: Problem in mapping fragments...: Each of the following columns in table PageView is mapped to multiple conceptual side properties: PageView.Version is mapped to (PageView_Association.View.Version, PageView_Association.Page.Version) So clearly enough, EF is having a complain about the Version column being a common component of the two foreign keys. Obviously I could create a PageVersion and ViewVersion column in the join table, but that kind of defeats the point of the constraint, i.e. the Page and View must have the same Version value. Has anyone encountered this, and is there anything I can do get around it? Thanks!

  Read the article

• How to improve performance of non-scalar aggregations on denormalized tables

  - by The Lazy DBA

  Suppose we have a denormalized table with about 80 columns, and grows at the rate of ~10 million rows (about 5GB) per month. We currently have 3 1/2 years of data (~400M rows, ~200GB). We create a clustered index to best suit retrieving data from the table on the following columns that serve as our primary key... [FileDate] ASC, [Region] ASC, [KeyValue1] ASC, [KeyValue2] ASC ... because when we query the table, we always have the entire primary key. So these queries always result in clustered index seeks and are therefore very fast, and fragmentation is kept to a minimum. However, we do have a situation where we want to get the most recent FileDate for every Region, typically for reports, i.e. SELECT [Region] , MAX([FileDate]) AS [FileDate] FROM HugeTable GROUP BY [Region] The "best" solution I can come up to this is to create a non-clustered index on Region. Although it means an additional insert on the table during loads, the hit isn't minimal (we load 4 times per day, so fewer than 100,000 additional index inserts per load). Since the table is also partitioned by FileDate, results to our query come back quickly enough (200ms or so), and that result set is cached until the next load. However I'm guessing that someone with more data warehousing experience might have a solution that's more optimal, as this, for some reason, doesn't "feel right".

  Read the article

• Eclipselink update existing tables

  - by javydreamercsw

  Maybe I got it wrong but i though that JPA was able to update an existing table (model changed adding a column) but is not working in my case. I can see in the logs eclipselink attempting to create it but failing because it already exists. Instead of trying an update to add the column it keeps going. (Had to remove some < so it displays) property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/jwrestling"/ property name="javax.persistence.jdbc.password" value="password"/ property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/ property name="javax.persistence.jdbc.user" value="user"/ property name="eclipselink.ddl-generation" value="create-tables"/ property name="eclipselink.logging.logger" value="org.eclipse.persistence.logging.DefaultSessionLog"/ property name="eclipselink.logging.level" value="INFO"/ And here's the table with the change (online column added) [EL Warning]: 2010-05-31 14:39:06.044--ServerSession(16053322)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.1.0.v20100517-r7246): org.eclipse.persistence.exceptions.DatabaseException Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'account' already exists Error Code: 1050 Call: CREATE TABLE account (ID INTEGER NOT NULL, USERNAME VARCHAR(32) NOT NULL, SECURITY_KEY VARCHAR(255) NOT NULL, EMAIL VARCHAR(64) NOT NULL, STATUS VARCHAR(8) NOT NULL, TIMEDATE DATETIME NOT NULL, PASSWORD VARCHAR(255) NOT NULL, ONLINE TINYINT(1) default 0 NOT NULL, PRIMARY KEY (ID)) Query: DataModifyQuery(sql="CREATE TABLE account (ID INTEGER NOT NULL, USERNAME VARCHAR(32) NOT NULL, SECURITY_KEY VARCHAR(255) NOT NULL, EMAIL VARCHAR(64) NOT NULL, STATUS VARCHAR(8) NOT NULL, TIMEDATE DATETIME NOT NULL, PASSWORD VARCHAR(255) NOT NULL, ONLINE TINYINT(1) default 0 NOT NULL, PRIMARY KEY (ID))") [EL Warning]: 2010-05-31 14:39:06.074--ServerSession(16053322)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.1.0.v20100517-r7246): org.eclipse.persistence.exceptions.DatabaseException After this it continues with the following. Am I doing something wrong or is a bug?

  Read the article

• whats wrong with this ruby hash?

  - by yaya3

  I'm pretty new to ruby, I keep getting the following error: in gem_original_require': ./helpers/navigation.rb:28: odd number list for Hash (SyntaxError) Any help appreciated... module Sinatra::Navigation def navigation @navigation nav = { primary[0] = { :title => "cheddar", :active => false, :children => { { :title => "cheese", :active => false }, { :title => "ham", :active => false } } }, primary[1] = { :title => "gorgonzola", :active => false, :children => { { :title => "What is the cheese?", :active => false }, { :title => "What cheese", :active => false }, { :title => "What does the cheese tell us?", :active => false, :children => { { :title => "Cheessus", :active => false }, { :title => "The impact of different cheeses / characteristics for cheese in relation to CHSE outcomes", :active => false } } } } } }

  Read the article

• Field specific errors for ETL

  - by AaronLS

  I am creating a ETL process in MS SQL Server and I would like to have errors specific to a particular column of a particular row. For example, the data is initially loaded from excel files into a table(we'll call the Initial table) where all columns are varchar(2000) and then I stage the data to another table(the DataTypedTable) that contains more specific data types (datetime,int, etc.) or more tightly constrained varchar lengths. I need to be able to create error messages for a specific field such as: "Jan. 13th" is not a valid date format for the submission date. Please use a format of MM/DD/YYYY These error messages would need to be stored in some way such that later in the process a automated process can create reports with the error messages such that each message references a specific row and field(someone will need to go back and correct the data in the source system and resubmit the excel file). So ideally it would be inserted into a Failures tables of some sort and contain the primary key of the failed row, the column name, and the error message. Question: So I am wondering if this can be accomplished with SSIS, or some open source tool like Talend, and if so, what would be your general approach? Or what hand coded approach you would take? Couple approaches I've thought of using SQL(up until no I have done ETL by hand in SQL procs, but I want to consider other approaches. Possible C# even.): Use a cursor to read through the Initial table, and for each row insert a blank record with only the primary key into the DataTyped table, then use a single update statement for each column, such that if that update fails I can insert a very specific error message specific to that column in the error messages table. Insert all the data as is into the DataTyped table, but have duplicate columns like SubmissionDate and SubmissionDateOld. After the initial insert the *Old columns have data, the rest are blank, and I have a single update for each column that sets the SubmissionDate based on the SubmissionDateOld. In addition to suggesting an approach, I'd like to know if you are using that approach or something similar already in the work you do.

  Read the article

• MYSQL fetch 10 posts, each w/ vote count, sorted by vote count, limited by where clause on posts

  - by nibblebot

  I want to fetch a set of Posts w/ vote count listed, sorted by vote count (e.g.) Post 1 - Post Body blah blah - Votes: 500 Post 2 - Post Body blah blah - Votes: 400 Post 3 - Post Body blah blah - Votes: 300 Post 4 - Post Body blah blah - Votes: 200 I have 2 tables: Posts - columns - id, body, is_hidden Votes - columns - id, post_id, vote_type_id Here is the query I've tried: SELECT p.*, v.yes_count FROM posts p LEFT JOIN (SELECT post_id, vote_type_id, COUNT(1) AS yes_count FROM votes WHERE (vote_type_id = 1) GROUP BY post_id ORDER BY yes_count DESC LIMIT 0, 10) v ON v.post_id = p.id WHERE (p.is_hidden = 0) ORDER BY yes_count DESC LIMIT 0, 10 Correctness: The above query almost works. The subselect is including votes for posts that have is_hidden = 1, so when I left join it to posts, if a hidden post is in the top 10 (ranked by votes), I can end up with records with NULL on the yes_count field. Performance: I have ~50k posts and ~500k votes. On my dev machine, the above query is running in .4sec. I'd like to stay at or below this execution time. Indexes: I have an index on the Votes table that covers the fields: vote_type_id and post_id EXPLAIN id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY p ALL NULL NULL NULL NULL 45985 Using where; Using temporary; Using filesort 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 10 2 DERIVED votes ref VotingPost VotingPost 4 319881 Using where; Using index; Using temporary; Using filesort

  Read the article

• Windows Screensaver Multi Monitor Problem

  - by Bryan

  I have a simple screensaver that I've written, which has been deployed to all of our company's client PCs. As most of our PCs have dual monitors, I took care to ensure that the screensaver ran on both displays. This works fine, however on some systems, where the primary screen has been swapped (to the left monitor), the screensaver only works on the left (primary) screen. The offending code is below. Can anyone see anything I've done wrong, or a better way of handling this? For info, the context of "this", is the screensaver form itself. // Make form full screen and on top of all other forms int minY = 0; int maxY = 0; int maxX = 0; int minX = 0; foreach (Screen screen in Screen.AllScreens) { // Find the bounds of all screens attached to the system if (screen.Bounds.Left < minX) minX = screen.Bounds.Left; if (screen.Bounds.Width > maxX) maxX = screen.Bounds.Width; if (screen.Bounds.Bottom < minY) minY = screen.Bounds.Bottom; if (screen.Bounds.Height > maxY) maxY = screen.Bounds.Height; } // Set the location and size of the form, so that it // fills the bounds of all screens attached to the system Location = new Point(minX, minY); Height = maxY - minY; Width = maxX - minX; Cursor.Hide(); TopMost = true;

  Read the article

• t-sql most efficient row to column? for xml path, pivot

  - by ajberry

  create table _orders ( OrderId int identity(1,1) primary key nonclustered ,CustomerId int ) create table _details ( DetailId int identity(1,1) primary key nonclustered ,OrderId int ,ProductId int ) insert into _orders (CustomerId) select 1 union select 2 union select 3 insert into _details (OrderId,ProductId) select 1,100 union select 1,158 union select 1,234 union select 2,125 union select 3,105 union select 3,101 union select 3,212 union select 3,250 -- select orderid ,REPLACE(( SELECT ' ' + CAST(ProductId as varchar) FROM _details d WHERE d.OrderId = o.OrderId ORDER BY d.OrderId,d.DetailId FOR XML PATH('') ),'&#x20;','') as Products from _orders o I am looking for the most performant way to turn rows into columns. I have a requirement to output the contents of the db (not actual schema above, but concept is similar) in both fixed width and delimited formats. The above FOR XML PATH query gives me the result I want, but when dealing with anything other than small amounts of data, can take awhile. I've looked at pivot but most of the examples I have found are aggregating information. I just to combine the child rows and tack them onto the parent. For example, for an order it would need to output: OrderId,Product1,Product2,Product3,etc Thoughts or suggestions? I am using SQL Server 2k5.

  Read the article

• t-sql most efficient row to column? crosstab for xml path, pivot

  - by ajberry

  I am looking for the most performant way to turn rows into columns. I have a requirement to output the contents of the db (not actual schema below, but concept is similar) in both fixed width and delimited formats. The below FOR XML PATH query gives me the result I want, but when dealing with anything other than small amounts of data, can take awhile. select orderid ,REPLACE(( SELECT ' ' + CAST(ProductId as varchar) FROM _details d WHERE d.OrderId = o.OrderId ORDER BY d.OrderId,d.DetailId FOR XML PATH('') ),'&#x20;','') as Products from _orders o I've looked at pivot but most of the examples I have found are aggregating information. I just want to combine the child rows and tack them onto the parent. I should also point out I don't need to deal with the column names either since the output of the child rows will either be a fixed width string or a delimited string. For example, given the following tables: OrderId CustomerId ----------- ----------- 1 1 2 2 3 3 DetailId OrderId ProductId ----------- ----------- ----------- 1 1 100 2 1 158 3 1 234 4 2 125 5 3 101 6 3 105 7 3 212 8 3 250 for an order I need to output: orderid Products ----------- ----------------------- 1 100 158 234 2 125 3 101 105 212 250 or orderid Products ----------- ----------------------- 1 100|158|234 2 125 3 101|105|212|250 Thoughts or suggestions? I am using SQL Server 2k5. Example Setup: create table _orders ( OrderId int identity(1,1) primary key nonclustered ,CustomerId int ) create table _details ( DetailId int identity(1,1) primary key nonclustered ,OrderId int ,ProductId int ) insert into _orders (CustomerId) select 1 union select 2 union select 3 insert into _details (OrderId,ProductId) select 1,100 union select 1,158 union select 1,234 union select 2,125 union select 3,105 union select 3,101 union select 3,212 union select 3,250 using FOR XML PATH: select orderid ,REPLACE(( SELECT ' ' + CAST(ProductId as varchar) FROM _details d WHERE d.OrderId = o.OrderId ORDER BY d.OrderId,d.DetailId FOR XML PATH('') ),'&#x20;','') as Products from _orders o which outputs what I want, however is very slow for large amounts of data. One of the child tables is over 2 million rows, pushing the processing time out to ~ 4 hours. orderid Products ----------- ----------------------- 1 100 158 234 2 125 3 101 105 212 250

  Read the article

• NHibernate Child items query using Parent Id

  - by thorkia

  So I have a set up similar to this questions: Parent Child Setup Everything works great when saving the parent and the children. However, I seem to have a problem when selecting the children. I can't seem to get all the children with a specific parent. This fails with: NHibernate.QueryException: could not resolve property: ParentEntity_id of: Test.Data.ChildEntity Here is my code: public IEnumerable<ChildEntity> GetByParent(ParentEntity parent) { using (ISession session = OrmHelper.OpenSession()) { return session.CreateCriteria<ChildEntity>().Add(Restrictions.Eq("ParentEntity_id ", parent.Id)).List<ChildEntity>(); } } Any help in building a proper function to get all the items would be appreciated. Oh, I am using Fluent NHibernate to construct the mappings - version 1 RTM and NHibernate 2.1.2 GA If you need more information, let me know. As per you request, my fluent mappings: public ParentEntityMap() { Id(x => x.Id); Map(x => x.Name); Map(x => x.Code).UniqueKey("ukCode"); HasMany(x => x.ChildEntity).LazyLoad() .Inverse().Cascade.SaveUpdate(); } public ChildEntityMap() { Id(x => x.Id); Map(x => x.Amount); Map(x => x.LogTime); References(x => x.ParentEntity); } That maps to the following 2 tables: CREATE TABLE "ParentEntity" ( Id integer, Name TEXT, Code TEXT, primary key (Id), unique (Code) ) CREATE TABLE "ChildEntity" ( Id integer, Amount NUMERIC, LogTime DATETIME, ParentEntity_id INTEGER, primary key (Id) ) The data store in SQLite.

  Read the article

• How should I design my MYSQL table/s?

  - by yaya3

  I built a really basic php/mysql site for an architect that uses one 'projects' table. The website showcases various projects that he has worked on. Each project contained one piece of text and one series of images. Original projects table (create syntax): CREATE TABLE `projects` ( `project_id` int(11) NOT NULL auto_increment, `project_name` text, `project_text` text, `image_filenames` text, `image_folder` text, `project_pdf` text, PRIMARY KEY (`project_id`) ) ENGINE=MyISAM AUTO_INCREMENT=8 DEFAULT CHARSET=latin1; The client now requires the following, and I'm not sure how to handle the expansions in my DB. My suspicion is that I will need an additional table. Each project now have 'pages'. Pages either contain... One image One "piece" of text One image and one piece of text. Each page could use one of three layouts. As each project does not currently have more than 4 pieces of text (a very risky assumption) I have expanded the original table to accommodate everything. New projects table attempt (create syntax): CREATE TABLE `projects` ( `project_id` int(11) NOT NULL AUTO_INCREMENT, `project_name` text, `project_pdf` text, `project_image_folder` text, `project_img_filenames` text, `pages_with_text` text, `pages_without_img` text, `pages_layout_type` text, `pages_title` text, `page_text_a` text, `page_text_b` text, `page_text_c` text, `page_text_d` text, PRIMARY KEY (`project_id`) ) ENGINE=MyISAM AUTO_INCREMENT=8 DEFAULT CHARSET=latin1; In trying to learn more about MYSQL table structuring I have just read an intro to normalization and A Simple Guide to Five Normal Forms in Relational Database Theory. I'm going to keep reading! Thanks in advance

  Read the article

• Oracle why does creating trigger fail when there is a field called timestamp?

  - by Omar Kooheji

  I've just wasted the past two hours of my life trying to create a table with an auto incrementing primary key bases on this tutorial, The tutorial is great the issue I've been encountering is that the Create Target fails if I have a column which is a timestamp and a table that is called timestamp in the same table... Why doesn't oracle flag this as being an issue when I create the table? Here is the Sequence of commands I enter: Creating the Table: CREATE TABLE myTable (id NUMBER PRIMARY KEY, field1 TIMESTAMP(6), timeStamp NUMBER, ); Creating the Sequence: CREATE SEQUENCE test_sequence START WITH 1 INCREMENT BY 1; Creating the trigger: CREATE OR REPLACE TRIGGER test_trigger BEFORE INSERT ON myTable REFERENCING NEW AS NEW FOR EACH ROW BEGIN SELECT test_sequence.nextval INTO :NEW.ID FROM dual; END; / Here is the error message I get: ORA-06552: PL/SQL: Compilation unit analysis terminated ORA-06553: PLS-320: the declaration of the type of this expression is incomplete or malformed Any combination that does not have the two lines with a the word "timestamp" in them works fine. I would have thought the syntax would be enough to differentiate between the keyword and a column name. As I've said I don't understand why the table is created fine but oracle falls over when I try to create the trigger... CLARIFICATION I know that the issue is that there is a column called timestamp which may or may not be a keyword. MY issue is why it barfed when I tried to create a trigger and not when I created the table, I would have at least expected a warning. That said having used Oracle for a few hours, it seems a lot less verbose in it's error reporting, Maybe just because I'm using the express version though. If this is a bug in Oracle how would one who doesn't have a support contract go about reporting it? I'm just playing around with the express version because I have to migrate some code from MySQL to Oracle.

  Read the article

• Mapping composite foreign keys in a many-many relationship, with overlapping components.

  - by Kirk Broadhurst

  I have a Page table and a View table. There is a many-many relationship between these two via a PageView table. Unfortunately all of these tables need to have composite keys (for business reasons). Page has a primary key of (PageCode, Version), View has a primary key of (ViewCode, Version). PageView obviously enough has PageCode, ViewCode, and Version. The FK to Page is (PageCode, Version) and the FK to View is (ViewCode, Version) Makes sense and works, but when I try to map this in Entity framework I get Error 3021: Problem in mapping fragments...: Each of the following columns in table PageView is mapped to multiple conceptual side properties: PageView.Version is mapped to (PageView_Association.View.Version, PageView_Association.Page.Version) So clearly enough, EF is having a complain about the Version column being a common component of the two foreign keys. Obviously I could create a PageVersion and ViewVersion column in the join table, but that kind of defeats the point of the constraint, i.e. the Page and View must have the same Version value. Has anyone encountered this, and is there anything I can do get around it? Thanks!

  Read the article

• Optimizing MySQL for ALTER TABLE of InnoDB

  - by schuilr

  Sometime soon we will need to make schema changes to our production database. We need to minimize downtime for this effort, however, the ALTER TABLE statements are going to run for quite a while. Our largest tables have 150 million records, largest table file is 50G. All tables are InnoDB, and it was set up as one big data file (instead of a file-per-table). We're running MySQL 5.0.46 on an 8 core machine, 16G memory and a RAID10 config. I have some experience with MySQL tuning, but this usually focusses on reads or writes from multiple clients. There is lots of info to be found on the Internet on this subject, however, there seems to be very little information available on best practices for (temporarily) tuning your MySQL server to speed up ALTER TABLE on InnoDB tables, or for INSERT INTO .. SELECT FROM (we will probably use this instead of ALTER TABLE to have some more opportunities to speed things up a bit). The schema changes we are planning to do is adding a integer column to all tables and make it the primary key, instead of the current primary key. We need to keep the 'old' column as well so overwriting the existing values is not an option. What would be the ideal settings to get this task done as quick as possible?

  Read the article

• Problems when I try to see databases in SQLite

  - by Sabau Andreea

  I created in code a database and two tables: static final String dbName="graficeCirculatie"; static final String ruteTable="Rute"; static final String colRuteId="RutaID"; static final String colRuta="Ruta"; static final String statiaTable="Statia"; static final String colStatiaID="StatiaID"; static final String colIdRuta="IdRuta"; static final String colStatia="Statia"; public DatabaseHelper(Context context) { super(context, dbName, null,33); } public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub db.execSQL("CREATE TABLE " + statiaTable + " (" + colStatiaID + " INTEGER PRIMARY KEY , " + colIdRuta + " INTEGER, " + colStatia + " TEXT)"); db.execSQL("CREATE TABLE " + ruteTable + "(" + colRuteId + " INTEGER PRIMARY KEY AUTOINCREMENT, " + colRuta + " TEXT);"); InsertDepts(db); } void InsertDepts(SQLiteDatabase db) { ContentValues cv = new ContentValues(); cv.put(colRuteId, 1); cv.put(colRuta, "Expres8"); db.insert(ruteTable, colRuteId, cv); cv.put(colRuteId, 2); cv.put(colRuta, "Expres2"); db.insert(ruteTable, colRuteId, cv); cv.put(colRuteId, 3); cv.put(colRuta, "Expres3"); db.insert(ruteTable, colRuteId, cv); } Now I want to see tables inputs from command line. I try in this way: C:\Program Files\Android\android-sdk\tools sqlite3 SQLite version 3.7.4 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite sqlite3 graficeCirculatie ... select * from ruteTable; And I got an error: Error: near "squlite3": syntax error. Can someone help me?

  Read the article

• How to reuse results with a schema for end of day stock-data

  - by Vishalrix

  I am creating a database schema to be used for technical analysis like top-volume gainers, top-price gainers etc.I have checked answers to questions here, like the design question. Having taken the hint from boe100 's answer there I have a schema modeled pretty much on it, thusly: Symbol - char 6 //primary Date - date //primary Open - decimal 18, 4 High - decimal 18, 4 Low - decimal 18, 4 Close - decimal 18, 4 Volume - int Right now this table containing End Of Day( EOD) data will be about 3 million rows for 3 years. Later when I get/need more data it could be 20 million rows. The front end will be asking requests like "give me the top price gainers on date X over Y days". That request is one of the simpler ones, and as such is not too costly, time wise, I assume. But a request like " give me top volume gainers for the last 10 days, with the previous 100 days acting as baseline", could prove 10-100 times costlier. The result of such a request would be a float which signifies how many times the volume as grown etc. One option I have is adding a column for each such result. And if the user asks for volume gain in 10 days over 20 days, that would require another table. The total such tables could easily cross 100, specially if I start using other results as tables, like MACD-10, MACD-100. each of which will require its own column. Is this a feasible solution? Another option being that I keep the result in cached html files and present them to the user. I dont have much experience in web-development, so to me it looks messy; but I could be wrong ( ofc!) . Is that a option too? Let me add that I am/will be using mod_perl to present the response to the user. With much of the work on mysql database being done using perl. I would like to have a response time of 1-2 seconds.

  Read the article

• tipfy for Google App Engine: Is it stable? Can auth/session components of tipfy be used with webapp?

  - by cv12

  I am building a web application on Google App Engine that requires users to register with the application and subsequently authenticate with it and maintain sessions. I don't want to force users to have Google accounts. Also, the target audience for the application is the average non-geek, so I'm not very keen on using OpenID or OAuth. I need something simple like: User registers with an e-mail and password, and then can log back in with those credentials. I understand that this approach does not provide the security benefits of Google or OpenID authentication, but I am prepared to trade foolproof security for end-user convenience and hassle-free experience. I explored Django, but decided that consecutive deprecations from appengine-helper to app-engine-patch to django-nonrel may signal that path may be a bit risky in the long-term. I'd like to use a code base that is likely to be maintained consistently. I also explored standalone session/auth packages like gaeutilities and suas. GAEUtilities looked a bit immature (e.g., the code wasn't pythonic in places, in my opinion) and SUAS did not give me a lot of comfort with the cookie-only sessions. I could be wrong with my assessment of these two, so I would appreciate input on those (or others that may serve my objective). Finally, I recently came across tipfy. It appears to be based on Werkzeug and Alex Martelli spoke highly of it here on stackoverflow. I have two primary questions related to tipfy: As a framework, is it as mature as webapp? Is it stable and likely to be maintained for some time? Since my primary interest is the auth/session components, can those components of the tipfy framework be used with webapp, independent of the broader tipfy framework? If yes, I would appreciate a few pointers to how I could go about doing that.

  Read the article

• Template compiling errors on iPhone SDK 3.2

  - by Didier Malenfant

  I'm porting over some templated code from Windows and I'm hitting some compiler differences on the iPhone 3.2 SDK. Original code inside a class template's member function is: return BinarySearch<uint32, CSimpleKey<T> >(key); where BinarySearch is a method inherited from another template. This produces the following error: csimplekeytable.h:131: error: no matching function for call to 'BinarySearch(NEngine::uint32&)' The visual studio compiler seems to walk up the template hierarchy fine but gcc needs me to fully qualify where the function comes from (I have verified this by fixing the same issues with template member variables that way). So I now need to change this into: return CSimpleTable<CSimpleKey<T> >::BinarySearch<uint32, CSimpleKey<T> >(key); Which now produces the following error: csimplekeytable.h:132: error: expected primary-expression before ',' token csimplekeytable.h:132: error: expected primary-expression before '>' token After some head scratching, I believe what's going on here is that it's trying to resolve the '<' before BinarySearch as a 'Less Than' operator for some reason. So two questions: - Am I on the right path with my interpretation of the error? - How do I fix it? -D

  Read the article

• TSQL Help (SQL Server 2005)

  - by Mick Walker

  I have been playing around with a quite complex SQL Statement for a few days, and have gotten most of it working correctly. I am having trouble with one last part, and was wondering if anyone could shed some light on the issue, as I have no idea why it isnt working: INSERT INTO ExistingClientsAccounts_IMPORT SELECT DISTINCT cca.AccountID, cca.SKBranch, cca.SKAccount, cca.SKName, cca.SKBase, cca.SyncStatus, cca.SKCCY, cca.ClientType, cca.GFCID, cca.GFPID, cca.SyncInput, cca.SyncUpdate, cca.LastUpdatedBy, cca.Deleted, cca.Branch_Account, cca.AccountTypeID FROM ClientsAccounts AS cca INNER JOIN (SELECT DISTINCT ClientAccount, SKAccount, SKDesc, SKBase, SKBranch, ClientType, SKStatus, GFCID, GFPID, Account_Open_Date, Account_Update FROM ClientsAccounts_IMPORT) AS ccai ON cca.Branch_Account = ccai.ClientAccount Table definitions follow: CREATE TABLE [dbo].[ExistingClientsAccounts_IMPORT]( [AccountID] [int] NOT NULL, [SKBranch] [varchar](2) NOT NULL, [SKAccount] [varchar](12) NOT NULL, [SKName] [varchar](255) NULL, [SKBase] [varchar](16) NULL, [SyncStatus] [varchar](50) NULL, [SKCCY] [varchar](5) NULL, [ClientType] [varchar](50) NULL, [GFCID] [varchar](10) NULL, [GFPID] [varchar](10) NULL, [SyncInput] [smalldatetime] NULL, [SyncUpdate] [smalldatetime] NULL, [LastUpdatedBy] [varchar](50) NOT NULL, [Deleted] [tinyint] NOT NULL, [Branch_Account] [varchar](16) NOT NULL, [AccountTypeID] [int] NOT NULL ) ON [PRIMARY] CREATE TABLE [dbo].[ClientsAccounts_IMPORT]( [NEWClientIndex] [bigint] NOT NULL, [ClientGroup] [varchar](255) NOT NULL, [ClientAccount] [varchar](255) NOT NULL, [SKAccount] [varchar](255) NOT NULL, [SKDesc] [varchar](255) NOT NULL, [SKBase] [varchar](10) NULL, [SKBranch] [varchar](2) NOT NULL, [ClientType] [varchar](255) NOT NULL, [SKStatus] [varchar](255) NOT NULL, [GFCID] [varchar](255) NULL, [GFPID] [varchar](255) NULL, [Account_Open_Date] [smalldatetime] NULL, [Account_Update] [smalldatetime] NULL, [SKType] [varchar](255) NOT NULL ) ON [PRIMARY] The error message I get is: Msg 8152, Level 16, State 14, Line 1 String or binary data would be truncated. The statement has been terminated.

  Read the article

• How do I add two alternating UITableViews to an existing UINavigationController view?

  - by Ron Flax

  I'm new to iPhone development and I am writing an iPhone app that needs two different table views, which are selectable using a button bar or tab bar. These table views are both the same size, but only cover about two thirds of the screen from the bottom up. The top portion of the screen remains the same when either of these tables is displayed. I'd also like to animate (flip) these views when the user selects one or the other. The view that these two tables will be displayed on is the detail view of my app where the user has already selected an item from the primary screen's table. I'm using a UINavigationController to manage the primary and detail views and I have this working. I also have the first of these two detail tables working as part of my detail view, but I think it makes more sense to isolate the code for these two tables and not duplicate all of the code for the part of the detail view that doesn't change. I don't really care how these two table views are created (either in code or via IB). I've tried several things and I can't seem to figure it out. Any help or ideas (with sample code) would be greatly appreciated!

  Read the article

< Previous Page | 296 297 298 299 300 301 302 303 304 305 306 307  | Next Page >