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  • 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.

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  • Ruby on Rails 2.3.5: Populating my prod and devel database with data (migration or fixture?)

    - by randombits
    I need to populate my production database app with data in particular tables. This is before anyone ever even touches the application. This data would also be required in development mode as it's required for testing against. Fixtures are normally the way to go for testing data, but what's the "best practice" for Ruby on Rails to ship this data to the live database also upon db creation? ultimately this is a two part question I suppose. 1) What's the best way to load test data into my database for development, this will be roughly 1,000 items. Is it through a migration or through fixtures? The reason this is a different answer than the question below is that in development, there's certain fields in the tables that I'd like to make random. In production, these fields would all start with the same value of 0. 2) What's the best way to bootstrap a production db with live data I need in it, is this also through a migration or fixture? I think the answer is to seed as described here: http://lptf.blogspot.com/2009/09/seed-data-in-rails-234.html but I need a way to seed for development and seed for production. Also, why bother using Fixtures if seeding is available? When does one seed and when does one use fixtures?

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  • Trying to convert existing production database table columns from enum to VARCHAR (Rails)

    - by dchua
    Hi everyone, I have a problem that needs me to convert my existing live production (I've duplicated the schema on my local development box, don't worry :)) table column types from enums to a string. Background: Basically, a previous developer left my codebase in absolute shit, migration versions are extremely out of date, and apparently he never used it after a certain point of time in development and now that I'm tasked with migrating a rails 1.2.6 app to 2.3.5, I can't get the tests to run properly on 2.3.5 because my table columns have ENUM column types and they convert to :string, :limit = 0 on my schema.rb which creates the problem of an invalid default value when doing a rake db:test:prepare, like in the case of: Mysql::Error: Invalid default value for 'own_vehicle': CREATE TABLE `lifestyles` (`id` int(11) DEFAULT NULL auto_increment PRIMARY KEY, `member_id` int(11) DEFAULT 0 NOT NULL, `own_vehicle` varchar(0) DEFAULT 'Y' NOT NULL, `hobbies` text, `sports` text, `AStar_activities` text, `how_know_IRC` varchar(100), `IRC_referral` varchar(200), `IRC_others` varchar(100), `IRC_rdrive` varchar(30)) ENGINE=InnoDB I'm thinking of writing a migration task that looks through all the database tables for columns with enum and replace it with VARCHAR and I'm wondering if this is the right way to approach this problem. I'm also not very sure how to write it such that it would loop through my database tables and replace all ENUM colum_types with a VARCHAR. References [1] https://rails.lighthouseapp.com/projects/8994/tickets/997-dbschemadump-saves-enum-columns-as-varchar0-on-mysql [2] http://dev.rubyonrails.org/ticket/2832

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  • WPF View/ViewModels using Generics- how?

    - by Investor5555
    New to WPF, so please bear with me... Suppose I have 2 tables in SQL Thing OtherThing Both have the exact same fields: ID (int) Name (string) Description (string) IsActive (bit/bool) DateModified (DateTime) So, I want to create one Model (not two) and do something like this: BaseModel<T>() { public int ID {get;set;} ... } etc. (of course, using the INotifyPropertyChanged, just trying to keep the code simple). I want to be able to create a BaseView and BaseViewModel that would work with whatever model conforms to the Thing/OtherThing. I am really at a loss as to what to do here to make this generic, so I don't have to have a ThingView/ThingViewModel and a OtherThingView/OtherThingViewModel... It seems that this should be simple, but I cannot seem to figure it out. Does anyone have a code example where they could interchange various items from a dropdown list using one view, one ViewModel, and one base datamodel (and switching out the type from a dropdown)? For example, a combobox has 3 identical table structures for Thing OtherThing SomeThing and on selection changed, I want to pull the data from whatever table was selected, to be able to do standard CRUD operations on any of these 3 tables, without having to create concrete classes for each view/viewmodel.

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  • Generating SQL change scripts in SSMS 2008

    - by Munish Goyal
    I have gone through many related SO threads and got some basic info. Already generated DB diagram. After that i am unable to find a button/option to generate SQL scripts (create) for all the tables in diagram. "Generate script" button is disabled, even on clicking the table in diagram. However i enabled the auto-generate option in tools-designer. But what to do with previous diagrams. I just want an easy way to auto-generate such scripts (create/alter) and would be gud if i get auto-generated stored procs for insert/selects/update etc. EDIT: I could do generate scripts for DB objects. Now: 1. How to import DB diagram from another DB. 2. How to generate (and manage their change integrated with VS source control) routine stored-procs like insert, update and select. Ok let me ask another way, can experts guide on the usual flow of creating/altering tables (across releases), creating stored-procs (are stored-procs the best way to go ?) and their change-management using SSMS design tools and minimal effort ?

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  • why DataColumn AllowDbNull is true even if oracle db does not allow null

    - by matti
    Hi. I have column SomeId in table SomeLink. When I look with tOra or Sql Plus Worksheet both state: tOra: Column name Data type Default Null Comment SOMEID INTEGER {null} NOT NULL {null} Sql Plus: SOMEID NOT NULL NUMBER(38) I have authored a method that's intended to give default values to all NOT NULL fields that don't have values: public static void GetDefaultValuesForNonNullColumns(DataRow row) { foreach(DataColumn col in row.Table.Columns) { if (Convert.IsDBNull(row[col]) && !col.AllowDBNull) { if (ColumnIsNumeric(col.DataType)) row[col] = 0; else if (col.DataType == typeof(DateTime)) row[col] = DateTime.Now; else if (col.DataType == typeof(String)) row[col] = string.Empty; else if (col.DataType == typeof(Char)) row[col] = ' '; else throw new Exception(string.Format("Unsupported column type: {0}", col.DataType)); } } } When SOMEID is handled in loop the AllowDBNull = true. I really can't understand. The table is created in DataSet like this: _someLinkAdptr = _dbFactory.CreateDataAdapter(); _someLinkAdptr.SelectCommand = _dbFactory.CreateCommand(); _someLinkAdptr.SelectCommand.Connection = _cnctn; _someLinkAdptr.SelectCommand.CommandText = GetSomeLinkSelectTxtAndParams(_someLinkAdptr.SelectCommand, UndefinedValue.ToString(), UndefinedValue.ToString()); Select command returns no rows. The idea is that I can then use commandbuilder to get InsertCommand without building it myself. The row is added to dataset's table like this: private static void CreateDocLink(int anId, int anotherId) { DataRow row = _someDataSet.Tables["SomeLink"].NewRow(); row["AnId"] = anId; row["AnotherId"] = anotherId; Utility.GetDefaultValuesForNonNullColumns(row); _someDataSet.Tables["SomeLink"].Rows.Add(row); } When DataAdapter is updated to oracle db I get: ORA-01400: cannot insert NULL into (SOMESCHEMA.SOMELINK.SOMEID) Cheers & BR -Matti

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  • Rolling back file moves, folder deletes and mysql queries

    - by Workoholic
    This has been bugging me all day and there is no end in sight. When the user of my php application adds a new update and something goes wrong, I need to be able to undo a complex batch of mixed commands. They can be mysql update and insert queries, file deletes and folder renaming and creations. I can track the status of all insert commands and undo them if an error is thrown. But how do I do this with the update statements? Is there a smart way (some design pattern?) to keep track of such changes both in the file structure and the database? My database tables are MyISAM. It would be easy to just convert everything to InnoDB, so that I can use transactions. That way I would only have to deal with the file and folder operations. Unfortunately, I cannot assume that all clients have InnoDB support. It would also require me to convert many tables in my database to InnoDB, which I am hesitant to do.

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  • MS Access 2003 - Failure to create MDE file: error VBA is corrupt?

    - by Justin
    Ok so this is a brand new snag I have run into. I am trying to launch a new MDE from my source MDB file, and it is locking up Access. So in my mdb, I am first compacting and repairing, and then selecting create a new mde (just as I have done many times before). It looks like it is starting the process, but never gets to where it compacts when it is done, and access is not responding. So after I force close the app, I look in the folder where I am trying to create the MDE to and I see there is a new access db1 file there. If I try to open that it gives me an error that says file not found, and then it says the Visual Basic for Applications is corrupt. The thing is, I just made a very simple adjustment to the code since last launching an mde, and after this I double and triple checked it...its not that because its just a simple open this form and close this one addition. I did however have my source mdb file on a disc that I copied to my laptop, and then tried to re link the tables to the network drive (had them linked to other tables on my local drive so that I could develop offline)?? PLEASE HELP!!!

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  • ASP.NET MVC Newbie: why isn't my model available when creating a strongly-typed view?

    - by Rax Olgud
    I'm starting with ASP.NET MVC, and working with NerdDinner as reference. I did the following: Created a new project Added a couple of tables Created LINQ to SQL for them Created a new controller My Models directory now contains MyModel.dbml, under which I have MyModel.designer.cs, that contains classes for models relating to both of my tables (let's call them Categories and Products). Now, under my new controller, I would like to create a strongly typed view. So for example I have the following code in my controller (for my application I must work by name, and the "Name" field is unique): public ActionResult Details(string name) { MyModelDataContext db = new MyModelDataContext(); Product user = db.Products.Single(t => t.Name == name); return View(user); } I would like to create a strongly-typed view. So I right-click the line "return View(user)", and choose "Add View...". I click "Create a strongly-typed view". When I click the dropdown of "View data class", I don't see my models, but only: MyProject.Controllers.AccountMembershipService MyProject.Controllers.FormsAuthenticationService What am I missing?

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  • Hibernate design to speed up querying of large dataset

    - by paddydub
    I currently have the below tables representing a bus network mapped in hibernate, accessed from a Spring MVC based bus route planner I'm trying to make my route planner application perform faster, I load all the above tables into Lists to perform the route planner logic. I would appreciate if anyone has any ideas of how to speed my performace Or any suggestions of another method to approach this problem of handling a large set of data Coordinate Connections Table (INT,INT,INT, DOUBLE)( Containing 50,000 Coordinate Connections) ID, FROMCOORDID, TOCOORDID, DISTANCE 1 1 2 0.383657 2 1 17 0.173201 3 1 63 0.258781 4 1 64 0.013726 5 1 65 0.459829 6 1 95 0.458769 Coordinate Table (INT,DECIMAL, DECIMAL) (Containing 4700 Coordinates) ID , LAT, LNG 0 59.352669 -7.264341 1 59.352669 -7.264341 2 59.350012 -7.260653 3 59.337585 -7.189798 4 59.339221 -7.193582 5 59.341408 -7.205888 Bus Stop Table (INT, INT, INT)(Containing 15000 Stops) StopID RouteID COORDINATEID 1000100001 100 17 1000100002 100 18 1000100003 100 19 1000100004 100 20 1000100005 100 21 1000100006 100 22 1000100007 100 23 This is how long it takes to load all the data from each table: stop.findAll = 148ms, stops.size: 15670 Hibernate: select coordinate0_.COORDINATEID as COORDINA1_2_, coordinate0_.LAT as LAT2_, coordinate0_.LNG as LNG2_ from COORDINATES coordinate0_ coord.findAll = 51ms , coordinates.size: 4704 Hibernate: select coordconne0_.COORDCONNECTIONID as COORDCON1_3_, coordconne0_.DISTANCE as DISTANCE3_, coordconne0_.FROMCOORDID as FROMCOOR3_3_, coordconne0_.TOCOORDID as TOCOORDID3_ from COORDCONNECTIONS coordconne0_ coordinateConnectionDao.findAll = 238ms ; coordConnectioninates.size:48132 Hibernate Annotations @Entity @Table(name = "STOPS") public class Stop implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "STOPID") private int stopID; @Column(name = "ROUTEID", nullable = false) private int routeID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "COORDINATEID", nullable = false) private Coordinate coordinate; } @Table(name = "COORDINATES") public class Coordinate { @Id @GeneratedValue @Column(name = "COORDINATEID") private int CoordinateID; @Column(name = "LAT") private double latitude; @Column(name = "LNG") private double longitude; } @Entity @Table(name = "COORDCONNECTIONS") public class CoordConnection { @Id @GeneratedValue @Column(name = "COORDCONNECTIONID") private int CoordinateID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "FROMCOORDID", nullable = false) private Coordinate fromCoordID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "TOCOORDID", nullable = false) private Coordinate toCoordID; @Column(name = "DISTANCE", nullable = false) private double distance; }

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  • Many to many table design question

    - by user169867
    Originally I had 2 tables in my DB, [Property] and [Employee]. Each employee can have 1 "Home Property" so the employee table has a HomePropertyID FK field to Property. Later I needed to model the situation where despite having only 1 "Home Property" the employee did work at or cover for multiple properties. So I created an [Employee2Property] table that has EmployeeID and PropertyID FK fields to model this many 2 many relationship. Now I find that I need to create other many-to-many relationships between employees and properties. For example if there are multiple employees that are managers for a property or multiple employees that perform maintenance work at a property, etc. My questions are: 1) Should I create seperate many-to-many tables for each of these situations or should I just create 1 more table like [PropertyAssociatonType] that lists the types of associations an emploee can have with a property and just add a FK field to [Employee2Property] such a PropertyAssociationTypeID that explains what the association is? I'm curious about the pros/cons or if there's another better way. 2) Am I stupid and going about this all worng? Thanks for any suggestions :)

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  • How do I write this MySQL query?

    - by CT
    I am working on an Asset DB using a lamp stack. In this example consider the following 5 tables: asset, server, laptop, desktop, software All tables have a primary key of id, which is a unique asset id. Every object has all asset attributes and then depending on type of asset has additional attributes in the corresponding table. If the type is a server, desktop or laptop it also has items in the software table. Here are the table create statements: // connect to mysql server and database "asset_db" mysql_connect("localhost", "asset_db", "asset_db") or die(mysql_error()); mysql_select_db("asset_db") or die(mysql_error()); // create asset table mysql_query("CREATE TABLE asset( id VARCHAR(50) PRIMARY KEY, company VARCHAR(50), location VARCHAR(50), purchase_date VARCHAR(50), purchase_order VARCHAR(50), value VARCHAR(50), type VARCHAR(50), notes VARCHAR(200))") or die(mysql_error()); echo "Asset Table Created.</br />"; // create software table mysql_query("CREATE TABLE software( id VARCHAR(50) PRIMARY KEY, software VARCHAR(50), license VARCHAR(50))") or die(mysql_error()); echo "Software Table Created.</br />"; // create laptop table mysql_query("CREATE TABLE laptop( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), serial_number VARCHAR(50), esc VARCHAR(50), user VARCHAR(50), prev_user VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Laptop Table Created.</br />"; // create desktop table mysql_query("CREATE TABLE desktop( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), serial_number VARCHAR(50), esc VARCHAR(50), user VARCHAR(50), prev_user VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Desktop Table Created.</br />"; // create server table mysql_query("CREATE TABLE server( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Server Table Created.</br />"; ?> How do I query the database so that if I search by id, I receive all related fields to that asset id? Thank you.

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  • LEFT OUTER JOIN with a WHERE clause

    - by Wesley
    I have two tables. indRailType contains a list of the names paired with an ID value that I use in other tables to indicate the rail type. WO_BreakerRail contains a date column and a rail code colume that corresponds to the same code in indRailType and some other data. There's a row in WO_BreakerRail for any activity on each rail type, for every date. So I could have 3 rows dated for 3/19/2010, each row indicates a different rail code, and what happened. When I use the following LEFT OUTER JOIN, I get a table with all the types of rail, with nulls in the rows where nothing happened on the 19th. Now, this is only working because I only have one date represented in my WO_BreakerRail table right now, the 19th. When I add more rows with different dates, things will go haywire. This is my SQL statement, which right now gives me exactly the results I want: SELECT WO_BreakerRail.ID, indRailType.RailType, WO_BreakerRail.CreatedPieces, WO_BreakerRail.OutsideSource, WO_BreakerRail.Charged, WO_BreakerRail.Rejected, WO_BreakerRail.RejectedToCrop FROM indRailType LEFT OUTER JOIN WO_BreakerRail ON indRailType.RailCode = WO_BreakerRail.RailCode Now, when I add in a WHERE WO_BreakerRail.Date = @Date clause I lose all the rows in the JOIN which nothing happened. I don't want that. From reading up, it sounds like a FULL OUTER JOIN is what I want, but SQL Server Compact Edition doesn't support FULL OUTER JOINs. Is there a way around this, or am I looking for something else entirely?

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  • Understanding many to many relationships and Entity Framework

    - by Anders Svensson
    I'm trying to understand the Entity Framework, and I have a table "Users" and a table "Pages". These are related in a many-to-many relationship with a junction table "UserPages". First of all I'd like to know if I'm designing this relationship correctly using many-to-many: One user can visit multiple pages, and each page can be visited by multiple users..., so am I right in using many2many? Secondly, and more importantly, as I have understood m2m relationships, the User and Page tables should not repeat information. I.e. there should be only one record for each user and each page. But then in the entity framework, how am I able to add new visits to the same page for the same user? That is, I was thinking I could simply use the Count() method on the IEnumerable returned by a LINQ query to get the number of times a user has visited a certain page. But I see no way of doing that. In Linq to Sql I could access the junction table and add records there to reflect added visits to a certain page by a certain user, as many times as necessary. But in the EF I can't access the junction table. I can only go from User to a Pages collection and vice versa. I'm sure I'm misunderstanding relationships or something, but I just can't figure out how to model this. I could always have a Count column in the Page table, but as far as I have understood you're not supposed to design database tables like that, those values should be collected by queries... Please help me understand what I'm doing wrong...

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  • Create bookmark into 1st column of MSWord table

    - by MikeD
    Hello All, does anyone have a VBA code to create a bookmark into the first column of an MSWord table? Let's say I have a table looking like this .-----.----------------. . ref . Title . .-----.----------------. . 1 . Title 1 . .-----.----------------. . 2 . Title 2 . .-----.----------------. . foo . Title 3 . .-----.----------------. . bar . Title 4 . .-----.----------------. and I want a VBA code fragment that creates a bookmark named "T1_1" on the string "1" in row 2 / column 1, and bookmarks named "T1_2", "T1_foo" and "T1_bar" on the strings in the other cells of column 1. I don't mind to hardcode the prefix "T1" (and substitute for other tables each time). I don't mind to select tables before running the macro, I don't mind giving those cells a special format, and I don't mind to get a superfluous bookmark "T1_ref" from the first row - so the code doesn't need to distinguish between table title and table row. Thanks a lot in advance

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  • SQL UNION ALL with a INNER JOIN

    - by kOhm
    I'm looking for the best way to display all rows from two tables while joining first by one field (dwg) then where applicable a 2nd join on part. Table1 data consists of schematics(dwg) along with a list of parts required to build the item depicted in the drawing. Table2 consists of data about the actual parts ordered to build the schematic. Some parts in table2 are a combination of parts in table1 (ex: foo and bar in table1 were ordered as foobar in table2). I can display all rows in both tables with UNION ALL, but this doesn't join on both the dwg and part fields. I looked at FULL OUTER JOIN also, but I haven't figured out how to join first by dwg, then by part. Here is an example of the data. table1 table2 dwg part qty order dwg part qty ----- ----- ----- ----- ----- ----- ----- 123 foo 1 ord1 123 foobar 1 123 bar 1 ord1 123 bracket 2 123 widget 2 ord2 123 screw 4 123 bracket 4 ord2 123 nut 4 456 foo 1 ord2 123 widget 2 ord2 123 bracket 2 ord3 456 foo 1 Desired output: The goal is to create a view that provides visibility to all parts in table1 and the associated orders in table2 (including those parts that appear in one but not the other table) so that I can see all the drawing parts in table1 and the associated records in table2 along with records in table2 where the part wasn't in table1. part_request_order_report dwg part qty order part qty ----- ----- ----- ------ ----- ----- 123 foo 1 123 bar 1 123 widget 2 ord2 widget 2 123 bracket 4 ord1 bracket 2 123 bracket 4 ord2 bracket 2 123 ord1 foobar 1 123 ord1 screw 4 123 ord1 nut 4 456 foo 1 ord3 foo 1 Is this possible? Or am I better off iterating through the data to build the report table? Thanks in advance.

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  • mysql whats wrong with this query?

    - by Hailwood
    I'm trying to write a query that selects from four tables campaignSentParent csp campaignSentEmail cse campaignSentFax csf campaignSentSms css Each of the cse, csf, and css tables are linked to the csp table by csp.id = (cse/csf/css).parentId The csp table has a column called campaignId, What I want to do is end up with rows that look like: | id | dateSent | emailsSent | faxsSent | smssSent | | 1 | 2011-02-04 | 139 | 129 | 140 | But instead I end up with a row that looks like: | 1 | 2011-02-03 | 2510340 | 2510340 | 2510340 | Here is the query I am trying SELECT csp.id id, csp.dateSent dateSent, COUNT(cse.parentId) emailsSent, COUNT(csf.parentId) faxsSent, COUNT(css.parentId) smsSent FROM campaignSentParent csp, campaignSentEmail cse, campaignSentFax csf, campaignSentSms css WHERE csp.campaignId = 1 AND csf.parentId = csp.id AND cse.parentId = csp.id AND css.parentId = csp.id; Adding GROUP BY did not help, so I am posting the create statements. csp CREATE TABLE `campaignsentparent` ( `id` int(11) NOT NULL AUTO_INCREMENT, `campaignId` int(11) NOT NULL, `dateSent` datetime NOT NULL, `account` int(11) NOT NULL, `status` varchar(15) NOT NULL DEFAULT 'Creating', PRIMARY KEY (`id`) ) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=latin1 cse/csf (same structure, different names) CREATE TABLE `campaignsentemail` ( `id` int(11) NOT NULL AUTO_INCREMENT, `parentId` int(11) NOT NULL, `contactId` int(11) NOT NULL, `content` text, `subject` text, `status` varchar(15) DEFAULT 'Pending', PRIMARY KEY (`id`) ) ENGINE=MyISAM AUTO_INCREMENT=140 DEFAULT CHARSET=latin1 css CREATE TABLE `campaignsentsms` ( `id` int(11) NOT NULL AUTO_INCREMENT, `parentId` int(11) NOT NULL, `contactId` int(11) NOT NULL, `content` text, `status` varchar(15) DEFAULT 'Pending', PRIMARY KEY (`id`) ) ENGINE=MyISAM AUTO_INCREMENT=141 DEFAULT CHARSET=latin1

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  • Database design MySQL using foreign keys

    - by dscher
    I'm having some a little trouble understanding how to handle the database end of a program I'm making. I'm using an ORM in Kohana, but am hoping that a generalized understanding of how to solve this issue will lead me to an answer with the ORM. I'm writing a program for users to manage their stock research information. My tables are basically like so: CREATE TABLE tags( id INT AUTO_INCREMENT NOT NULL PRIMARY KEY, tags VARCHAR(30), UNIQUE(tags) ) ENGINE=INNODB DEFAULT CHARSET=utf8; CREATE TABLE stock_tags( id INT AUTO_INCREMENT NOT NULL PRIMARY KEY, tag_id INT NOT NULL, stock_id INT NOT NULL, FOREIGN KEY (tag_id) REFERENCES tags(id), FOREIGN KEY(stock_id) REFERENCES stocks(id) ON DELETE CASCADE ) ENGINE=INNODB DEFAULT CHARSET=utf8; CREATE TABLE notes( id INT AUTO_INCREMENT NOT NULL, stock_id INT NOT NULL, notes TEXT NOT NULL, FOREIGN KEY (stock_id) REFERENCES stocks(id) ON DELETE CASCADE, PRIMARY KEY(id) ) ENGINE=INNODB DEFAULT CHARSET=utf8; CREATE TABLE links( id INT AUTO_INCREMENT NOT NULL, stock_id INT NOT NULL, links VARCHAR(2083) NOT NULL, FOREIGN KEY (stock_id) REFERENCES stocks(id) ON DELETE CASCADE, PRIMARY KEY(id) ) ENGINE=INNODB DEFAULT CHARSET=utf8; How would I get all the attributes of a single stock, including its links, notes, and tags? Do I have to add links, notes, and tags columns to the stocks table and then how do you call it? I know this differs using an ORM and I'd assume that I can use join tables in SQL. Thanks for any help, this will really help me understand the issue a lot better.

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  • what is a RoR best practice? match by id or different column?

    - by Omnipresent
    I had a terrible morning. Lots of emails floating around about why things don't work. Upon investigating I found that there is a data mismatch which is causing errors. Scenario Customer and Address are two tables. Customer contains class Customer < ActiveRecord::Base has_one :address, :foreign_key => "id" end Address Contains class Address < ActiveRecord::Base belongs_to :customer, :foreign_key => "cid" end So the two tables match on id which is the default and that column is auto incremented. Problem on the edit Page we have some code like this. params[:line1] = @customer.first.address.line1 It fails because no matching record is found for a customer in the address table. I don't know why this is happening. It seems that over time a lot of records did not get added to Address table. Now problem is that when a new Customer is added (say with id 500) the Address will be added with some other id (say 425) ...now you don't know which address belongs to which customer. Question Being new to Rails, I am asking whether it is always considered good to create an extra column for joining of the records, rather than depending on the column that is automatically incremented? If I had a seperate column in Address table where I would manually insert the recently added customers id then this issue would not have come up.

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  • how to design a schema where the columns of a table are not fixed

    - by hIpPy
    I am trying to design a schema where the columns of a table are not fixed. Ex: I have an Employee table where the columns of the table are not fixed and vary (attributes of Employee are not fixed and vary). Nullable columns in the Employee table itself i.e. no normalization Instead of adding nullable columns, separate those columns out in their individual tables ex: if Address is a column to be added then create table Address[EmployeeId, AddressValue]. Create tables ExtensionColumnName [EmployeeId, ColumnName] and ExtensionColumnValue [EmployeeId, ColumnValue]. ExtensionColumnName would have ColumnName as "Address" and ExtensionColumnValue would have ColumnValue as address value. Employee table EmployeeId Name ExtensionColumnName table ColumnNameId EmployeeId ColumnName ExtensionColumnValue table EmployeeId ColumnNameId ColumnValue There is a drawback is the first two ways as the schema changes with every new attribute. Note that adding a new attribute is frequent. I am not sure if this is the good or bad design. If someone had a similar decision to make, please give an insight on things like foreign keys / data integrity, indexing, performance, reporting etc.

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  • How to do binding programmically?

    - by user175908
    Hello, Could anyone identify the problem in this code? (I'm kinda newbie in WPF bindings.) This code executes after chart is loaded when I click a button: I get this error: Update: I dont get that error anymore. Thanks to Tomas. Now no error occur but chart looks completely blank (no columns) Update: Code now looks like this: // create a very simple DataSet var dataSet = new DataSet("MyDataSet"); var table = dataSet.Tables.Add("MyTable"); table.Columns.Add("Name"); table.Columns.Add("Price"); table.Rows.Add("Brick", 1.5d); table.Rows.Add("Soap", 4.99d); table.Rows.Add("Comic Book", 0.99d); // chart series var series = new ColumnSeries() { IndependentValueBinding = new Binding("[Name]"), // How to deal with DependentValueBinding = new Binding("[Price]"), // these two? ItemsSource = dataSet.Tables[0].DefaultView // or maybe I do mistake here? }; // ---------- set additional binding as adviced ------------------ series.SetBinding(ColumnSeries.ItemsSourceProperty, new Binding()); // chart stuff MyChart.Series.Add(series); MyChart.Title = "Names 'n Prices"; // some code to remove legend var style = new Style(typeof(Control)); style.Setters.Add(new Setter(LegendItem.TemplateProperty, null)); MyChart.LegendStyle = style; XAML: <Window x:Class="BindingzTest.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="606" Width="988" xmlns:charting="clr-namespace:System.Windows.Controls.DataVisualization.Charting;assembly=System.Windows.Controls.DataVisualization.Toolkit"> <Grid Name="LayoutRoot"> <charting:Chart Name="MyChart" Margin="0,0,573,0" Height="289" VerticalAlignment="Top" /> <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="272,361,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="chart1_Loaded" /> </Grid> Thanks for help in advance once more.

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  • Improve speed of a JOIN in MySQL

    - by ran2
    Dear all, I know there a similar threads around, but this is really the first time I realize that query speed might affect me - so it´s not that easy for me to really make the transfer from other folks problems. That being said I have using the following query successfully with smaller data, but if I use it on what are mildly large tables (about 120,000 records). I am waiting for hours. INSERT INTO anothertable (id,someint1,someint1,somevarchar1,somevarchar1) SELECT DISTINCT md.id,md.someint1,md.someint1,md.somevarchar1,pd.somevarchar1 from table1 AS md JOIN table2 AS pd ON (md.id = pd.id); Tables 1 and 2 contain about 120,000 records. The query has been running for almost 2 hours right now. Is this normal? Do I just have to wait. I really have no idea, but I am pretty sure that one could do it better since it´s my very first try. I read about indexing, but dont know yet what to index in my case? Thanks for any suggestions - feel free to point my to the very beginners guides ! best matt

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  • What is a good approach to preloading data?

    - by Bob Horn
    Are there best practices out there for loading data into a database, to be used with a new installation of an application? For example, for application foo to run, it needs some basic data before it can even be started. I've used a couple options in the past: TSQL for every row that needs to be preloaded: IF NOT EXISTS (SELECT * FROM Master.Site WHERE Name = @SiteName) INSERT INTO [Master].[Site] ([EnterpriseID], [Name], [LastModifiedTime], [LastModifiedUser]) VALUES (@EnterpriseId, @SiteName, GETDATE(), @LastModifiedUser) Another option is a spreadsheet. Each tab represents a table, and data is entered into the spreadsheet as we realize we need it. Then, a program can read this spreadsheet and populate the DB. There are complicating factors, including the relationships between tables. So, it's not as simple as loading tables by themselves. For example, if we create Security.Member rows, then we want to add those members to Security.Role, we need a way of maintaining that relationship. Another factor is that not all databases will be missing this data. Some locations will already have most of the data, and others (that may be new locations around the world), will start from scratch. Any ideas are appreciated.

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  • Load SQL query result data into cache in advance

    - by Marc
    I have the following situation: .net 3.5 WinForm client app accessing SQL Server 2008 Some queries returning relatively big amount of data are used quite often by a form Users are using local SQL Express and restarting their machines at least daily Other users are working remotely over slow network connections The problem is that after a restart, the first time users open this form the queries are extremely slow and take more or less 15s on a fast machine to execute. Afterwards the same queries take only 3s. Of course this comes from the fact that no data is cached and must be loaded from disk first. My question: Would it be possible to force the loading of the required data in advance into SQL Server cache? Note My first idea was to execute the queries in a background worker when the application starts, so that when the user starts the form the queries will already be cached and execute fast directly. I however don't want to load the result of the queries over to the client as some users are working remotely or have otherwise slow networks. So I thought just executing the queries from a stored procedure and putting the results into temporary tables so that nothing would be returned. Turned out that some of the result sets are using dynamic columns so I couldn't create the corresponding temp tables and thus this isn't a solution. Do you happen to have any other idea?

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  • Programming methods design phase assignment

    - by Shakir
    Hey, i have an assignment (NCC) which deals with the design phase. The Scenario is that you have four soccer divisions (divisions 1,2,3 and 4) which consist of 22 teams each and hence each team plays 42 games (home and away). The concept is similar to the barclays premier league whereby ranking is based on points or else goal difference or else goals scored by team. The difference is that the top 2 teams are promoted and the bottom 2 are relegated and this includes Div 1 and Div 4 as the top 2 of Div1 are promoted to the national league which is above division 1 regional league and bottom 2 of Div4 are relegated to the local league below Division 4 regional league. Hence there are 3 total leagues and 4 divisions in the regional league (which has 22 teams each). Now the referee has to add the result of the match and thus automatic tables have to be generated now, There are two reports League Tables for 4 divisions List of all results for any chosen team during the season by date it was played on There are a couple of things to be done... i know its gonna be terrible to make everything but atleast explain to me how i should go about drawing these and what things i should include (generally) Logical Data Structure Diagram (DSD) for each report Preliminary Program Structure (PSD) for each report Detailed Program Specification for each report Flowchart for each report There are other things but i think our teacher will give us clear "clues" for it Thanks a lot Update - Project so far: Data Structure Diagram Preliminary Program Structure

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