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• Real-world examples of populating a GWT CellTable using a clean MVP pattern?

  - by piehole

  We are using the GWT-Presenter framework and attempting to use CellTable to put together an updateable grid. It seems as though several of the GWT constructs for CellTable don't lend themselves to easily breaking up the logic into clean view and presenter code. Examples: 1) Within the View's constructor, the CellTable is defined and each column is created by anonymous inner classes that extend the Column class to provide the onValue() method. 2) The FieldUpdater interface must be implemented to provide logic to execute when a user alters data in a cell. This seems like it would best fit in the Presenter's onBind() method, but FieldUpdaters often need access to the Cell or Column which belong in the view. CellTable does not have accessor methods to get hold of the Columns or Cells, so it seems the only way for the Presenter to get them is for me to create a multitude of member variables on the View and accessors on my Display interface. Can anyone provide good examples for dealing with CellTable in GWT-Presenter or a comparable MVP

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• using dummy row with NOT NULL to solve DEFAUT NULL

  - by Tony38

  I know having DEFAULT NULLS is not a good practice but I have many optional lookup values which are FK in the system so to solve this issue here is what i am doing: I use NOT NULL for every FK / lookup valve field. I have the first row in every table which is PK id = 1 as a dummy row with just "none" in all the columns. this way I can use NOT NULL in my schema and if needed reference to the none row values which should be null. Is this a good design or any other work arounds?

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• Which index is used in select and why?

  - by Lukasz Lysik

  I have the table with zip codes with following columns: id - PRIMARY KEY code - NONCLUSTERED INDEX city When I execute query SELECT TOP 10 * FROM ZIPCodes I get the results sorted by id column. But when I change the query to: SELECT TOP 10 id FROM ZIPCodes I get the results sorted by code column. Again, when I change the query to: SELECT TOP 10 code FROM ZIPCodes I get the results sorted by code column again. And finally when I change to: SELECT TOP 10 id,code FROM ZIPCodes I get the results sorted by id column. My question is in the title of the question. I know which indexes are used in the queries, but my question is, why those indexes are used? I the second query (SELECT TOP 10 id FROM ZIPCodes) wouldn't it be faster if the clusteder index was used? How the query engine chooses which index to use?

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• using regular expression / Remove special characters with linq to sql

  - by Prasad

  How can i use regular expressions with linq to sql in the asp.net mvc(C#) application? The columns in my MSSQL table (Products) has some special characters like (, - % ',.....). While searching for a product i need to search without that special chareters. For ex.: I have a product say (ABC-Camp's / One), when i search for "abccamp", it should pull the product. I am trying the query like: from p in _context.pu_Products where p.User_Id == userId && p.Is_Deleted == false && p.Product_Name.ToLower().Contains(text.ToLower()) select new Product { ProductId = p.Product_Id, ProductName = p.Product_Name.Replace("’", "").Replace("\"", ""), RetailPrice = p.Retail_Price ?? 0M, LotSize = p.Lot_Size > 0 ? p.Lot_Size ?? 1 : 1, QuantityInHand = p.Quantity_In_Hand ?? 0 } But i need to search without any special characters...

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• Restricting deletion with NHibernate

  - by FrontSvin

  I'm using NHibernate (fluent) to access an old third-party database with a bunch of tables, that are not related in any explicit way. That is a child tables does have parentID columns which contains the primary key of the parent table, but there are no foreign key relations ensuring these relations. Ideally I would like to add some foreign keys, but cannot touch the database schema. My application works fine, but I would really like impose a referential integrity rule that would prohibit deletion of parent objects if they have children, e.i. something similar 'ON DELETE RESTRICT' but maintained by NHibernate. Any ideas on how to approach this would be appreciated. Should I look into the OnDelete() method on the IInterceptor interface, or are there other ways to solve this? Of course any solution will come with a performance penalty, but I can live with that.

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• How do I pass references as method parameters across AppDomains?

  - by Thiado de Arruda

  I have been trying to get the following code to work(everything is defined in the same assembly) : namespace SomeApp{ public class A : MarshalByRefObject { public byte[] GetSomeData() { // } } public class B : MarshalByRefObject { private A remoteObj; public void SetA(A remoteObj) { this.remoteObj = remoteObj; } } public class C { A someA = new A(); public void Init() { AppDomain domain = AppDomain.CreateDomain("ChildDomain"); string currentAssemblyPath = Assembly.GetExecutingAssembly().Location; B remoteB = domain.domain.CreateInstanceFromAndUnwrap(currentAssemblyPath,"SomeApp.B") as B; remoteB.SetA(someA); // this throws an ArgumentException "Object type cannot be converted to target type." } } } What I'm trying to do is pass a reference of an 'A' instance created in the first AppDomain to the child domain and have the child domain execute a method on the first domain. In some point on 'B' code I'm going to call 'remoteObj.GetSomeData()'. This has to be done because the 'byte[]' from 'GetSomeData' method must be 'calculated' on the first appdomain. What should I do to avoid the exception, or what can I do to achieve the same result?

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• How to Audit Database Activity without Performance and Scalability Issues?

  - by GotoError

  I have a need to do auditing all database activity regardless of whether it came from application or someone issuing some sql via other means. So the auditing must be done at the database level. The database in question is Oracle. I looked at doing it via Triggers and also via something called Fine Grained Auditing that Oracle provides. In both cases, we turned on auditing on specific tables and specific columns. However, we found that Performance really sucks when we use either of these methods. Since auditing is an absolute must due to regulations placed around data privacy, I am wondering what is best way to do this without significant performance degradations. If someone has Oracle specific experience with this, it will be helpful but if not just general practices around database activity auditing will be okay as well.

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• Breaking up large DataGridView for printing

  - by Hal

  Hey, I've got a single-row, 40 column-long DataGridView that i need to print. Since i can neither print it directly (because A4 sheets won't cut it ;)) nor adjust its width to the width of the page itself (because the headers look terrible), i wanted to break the DataGridView to 4 separate pieces and display 10 columns per row (imagine: column 1 to 10 in the first line, column 11 to 21 four or five lines below, etc...). Is there an easy way to do this? I was leaning towards a more manual approach (using fors), but i'd love to know if there's a more elegant way. Cheers

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• C# MVVM Calculating Total

  - by LnDCobra

  I need to calculate a trade value based on the selected price and quantity. How can The following is my ViewModel: class ViewModel : ViewModelBase { public Trade Trade { get { return _trade; } set { SetField(ref _trade, value, () => Trade); } } private Trade _trade; public decimal TradeValue { get { return Trade.Amount * Trade.Price; } } } ViewModelBase inherits INotifyPropertyChanged and contains SetField() The Following is the Trade class: public class Trade : INotifyPropertyChaged { public virtual Decimal Amount { get { return _amount; } set { SetField(ref _amount, value, () => Amount); } } private Decimal _amount; public virtual Decimal Price { get { return _price; } set { SetField(ref _price, value, () => Price); } } private Decimal _price; ...... } I know due to the design my TradeValue only gets calculated once (when its first requested) and UI doesn't get updated when amount/price changes. What is the best way of achieving this? Any help greatly appreciated.

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• Timestamps and Intervals: NUMTOYMINTERVAL SYSTDATE CALCULATION SQL QUERY

  - by MeachamRob

  I am working on a homework problem, I'm close but need some help with a data conversion I think. Or sysdate - start_date calculation The question is: Using the EX schema, write a SELECT statement that retrieves the date_id and start_date from the Date_Sample table (format below), followed by a column named Years_and_Months_Since_Start that uses an interval function to retrieve the number of years and months that have elapsed between the start_date and the sysdate. (Your values will vary based on the date you do this lab.) Display only the records with start dates having the month and day equal to Feb 28 (of any year). DATE_ID START_DATE YEARS_AND_MONTHS_SINCE_START 2 Sunday , February 28, 1999 13-8 4 Monday , February 28, 2005 7-8 5 Tuesday , February 28, 2006 6-8 Our EX schema that refers to this question is simply a Date_Sample Table with two columns: DATE_ID NUMBER NOT Null START_DATE DATE I Have written this code: SELECT date_id, TO_CHAR(start_date, 'Day, MONTH DD, YYYY') AS start_date , NUMTOYMINTERVAL((SYSDATE - start_date), 'YEAR') AS years_and_months_since_start FROM date_sample WHERE TO_CHAR(start_date, 'MM/DD') = '02/28'; But my Years and months since start column is not working properly. It's getting very high numbers for years and months when the date calculated is from 1999-ish. ie, it should be 13-8 and I'm getting 5027-2 so I know it's not correct. I used NUMTOYMINTERVAL, which should be correct, but don't think the sysdate-start_date is working. Data Type for start_date is simply date. I tried ROUND but maybe need some help to get it right. Something is wrong with my calculation and trying to figure out how to get the correct interval there. Not sure if I have provided enough information to everyone but I will let you know if I figure it out before you do. It's a question from Murach's Oracle and SQL/PL book, chapter 17 if anyone else is trying to learn that chapter. Page 559.

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• Using Rails, how can I set my primary key to not be an integer-typed column?

  - by Rudd Zwolinski

  I'm using Rails migrations to manage a database schema, and I'm creating a simple table where I'd like to use a non-integer value as the primary key (in particular, a string). To abstract away from my problem, let's say there's a table employees where employees are identified by an alphanumeric string, e.g. "134SNW". I've tried creating the table in a migration like this: create_table :employees, {:primary_key => :emp_id} do |t| t.string :emp_id t.string :first_name t.string :last_name end What this gives me is what seems like it completely ignored the line t.string :emp_id and went ahead and made it an integer column. Is there some other way to have rails generate the PRIMARY_KEY constraint (I'm using PostgreSQL) for me, without having to write the SQL in an execute call? NOTE: I know it's not best to use string columns as primary keys, so please no answers just saying to add an integer primary key. I may add one anyway, but this question is still valid.

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• Selecting data effectively sql

  - by learner135

  Hi, I have a very large table with over 1000 records and 200 columns. When I try to retreive records matching some criteria in the WHERE clause using SELECT statement it takes a lot of time. But most of the time I just want to select a single record that matches the criteria in the WHERE clause rather than all the records. I guess there should be a way to select just a single record and exit which would minimize the retrieval time. I tried ROWNUM=1 in the WHERE clause but it didn't really work cause I guess the engine still checks all the records even after finding the first record matching the WHERE criteria. Is there a way to optimize in case if I want to select just a few records? Thanks in advance. Edit: I am using oracle 10g.

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• Subquery vs Traditional join with WHERE clause?

  - by BradC

  When joining to a subset of a table, any reason to prefer one of these formats over the other? Subquery version: SELECT ... FROM Customers AS c INNER JOIN (SELECT * FROM Classification WHERE CustomerType = 'Standard') AS cf ON c.TypeCode = cf.Code INNER JOIN SalesReps s ON cf.SalesRepID = s.SalesRepID vs the WHERE clause at the end: SELECT ... FROM Customers AS c INNER JOIN Classification AS cf ON c.TypeCode = cf.Code INNER JOIN SalesReps AS s ON cf.SalesRepID = s.SalesRepID WHERE cf.CustomerType = 'Standard' The WHERE clause at the end feels more "traditional", but the first is arguably more clear, especially as the joins get increasingly complex. Only other reason I can think of to prefer the second is that the "SELECT *" on the first might be returning columns that aren't used later (In this case, I'd probably only need to return cf.Code and Cf.SalesRepID)

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• How do you calculate expanding mean on time series using pandas?

  - by mlo

  How would you create a column(s) in the below pandas DataFrame where the new columns are the expanding mean/median of 'val' for each 'Mod_ID_x'. Imagine this as if were time series data and 'ID' 1-2 was on Day 1 and 'ID' 3-4 was on Day 2. I have tried every way I could think of but just can't seem to get it right. left4 = pd.DataFrame({'ID': [1,2,3,4],'val': [10000, 25000, 20000, 40000],'Mod_ID': [15, 35, 15, 42], 'car': ['ford','honda', 'ford', 'lexus']}) right4 = pd.DataFrame({'ID': [3,1,2,4],'color': ['red', 'green', 'blue', 'grey'], 'wheel': ['4wheel','4wheel', '2wheel', '2wheel'], 'Mod_ID': [15, 15, 35, 42]}) df1 = pd.merge(left4, right4, on='ID').drop('Mod_ID_y', axis=1)

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• how to get the value entered in combobox that is binded to datagridview

  - by Ranjana

  i have dynamically added combobox to datagridview. in this gridview i need to enter the values to combobox. but it is not allowing me to enter the value. code: if (strtype.Contains("ComboBox")) { checkcmbColumn.Name = strControlName; checkcmbColumn.HeaderText = strColumnName; checkcmbColumn.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter; checkcmbColumn.Width = 100; checkcmbColumn.ReadOnly = false; checkcmbColumn.Items.Add("1"); checkcmbColumn.Items.Add("2"); GrdViewDetails.Columns.Add(checkcmbColumn); }

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• Return cell reference as result of if statement with vlookups.

  - by EMJ

  I have two sets of data in excel. One contains a set of data which represents the initial step of a process. The other set of data represents the additional steps which take place after the first step is completed. Each of the data records in the "additional step data" has an id in a column. I need to find the identifying codes of the "additional step data" which correspond with the initial step data records. The problem is that I have to match the data in 4 columns between the two data sets and return the id of the "additional step data". I started by doing a combination of an if and vlookup functions, but I got stuck when I tried to figure out how to get the if statement to reference the id of the matching "additional step data". Basically I am trying to avoid having to search by manually filtering between two sets of data and finding corresponding records. Does anyone have any idea about how to do this?

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• Very basic database theory.

  - by John R

  I have a set of tables to show the relationship between organziations and supporters below. Although I have done some basic mySQL querries, I know very little about database 'design'. I plan to querry the database for: -a list of contributors to a specific organization... or, -a list of organizations that a specific suporter supports. The database tables for organiations and contributors may have other columns in the future and recieve a lesser amount of querries based on that information. A | X A | Y A | Z B | X B | Y C | X C | Z How should the tables be set up? I assume that there should be a third table, but there is still redundent information in the third table. Is there a better way of setting up the tables? +----+-------+ +-------------+----------+ +----+-------+ | id | org | | org | contr | | id | contr.| +----+-------+ +-------------+----------+ +----+-------+ | 1 | A | | 1 | 1 | | 1 | X | | 2 | B | | 1 | 2 | | 2 | Y | | 3 | C | | 1 | 3 | | 3 | Z | +----+-------+ | 2 | 1 | +----+-------+ | 2 | 2 | | 3 | 1 | | 3 | 3 | +-------------+----------+

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• Forcing size of a complex Flash object.

  - by John

  As I've found recently, setting width/height properties on a Sprite only forces the Sprite to fit the given dimensions by scaling the actual size, which is calculated by Flash based on the rendered content. This leaves me confused. If I have a custom Sprite subclass which draws using Graphics, how can I do layout before an initial render - the size will be zero until it is first drawn? For a more complex issue, let's say I have a 2D game world with objects spread over a wide area with world coordinates from (0,0) to (5000,5000), where each object has a size of maybe up to 100x100. I want to have a Flash component which is the "game window", and has a fixed size like 400x300, rendering part of the game world. So how do I force the game window size to 400x300 pixels? I can draw a 400x300 rectangle to get the size correct but then if I draw any objects which are partly in-view, they can screw this up. Is the right approach to provide a custom setSize(w,h) method which is used rather than width & height setters? But even so, is there no way to make a Sprite force to the size I want? Do you really have to catch it every render and re-scale it?

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• Reading variable with double float precision from a text file with gnuplot

  - by user3636322

  I have a text file, containing data in 3 columns like below: 0.0100000000 | 0.0058077299 | -0.0000000288 0.0110000000 | 0.0075128707 | -0.0000000373 0.0120000000 | 0.0093579693 | -0.0000000465 I want to get the variables from this file in gnuplot and use them to draw graphs: What I exactly do is like below (e.g: to pick the variable from row 2 column 3): ii= 2 a_0 = system("awk '{ if (NR == " . ii . ") printf \"%f\", $3}' " .datafile) a_0 = a_0+0. but what is written as a_0 is zero! How can I increase the precision to get the exact value?

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• Getting started with MIT Proto

  - by Charles

  MIT Proto lacks a basic getting started guide. How do I find a shell that accepts commands like (def foo...) and proto -n 1000 -l -m ...? http://groups.csail.mit.edu/stpg/proto.html I can run in my bash shell: ./proto -n 1000 -s 0.1 -T -l "(red (gradient (= (mid) 0)))" I can't figure out how to run e.g. channel.proto: (def channel (src dst width) (let* ((d (distance src dst)) (trail (<= (+ (gradient src) (gradient dst)) (+ d 0.01))) ;; float error ;; (trail (= (+ (gradient src) (gradient dst)) d)) ) (dilate trail width))) ;; To see a channel calculated from geometric primitives, run: ;; proto -n 1000 -l -m -s 0.5 "(blue (channel (sense 1) (sense 2) 10))" ;; click on a device and hit 't' to set up the source, then click on ;; another device and hit 'y' to designate the destination. At first ;; every device will be blue, but then it should clear and you should ;; see a thick blue path connecting the two devices you selected. Thanks! P.S. Somebody please tag this mit-proto. I can't.

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• Conditional PIVOT/transform problem

  - by IanC

  Hi folks I have a table with three columns, which we'll call ID1, ID2, and Value. Sample data: ID ID1 Value 1 1 0 1 2 1 1 3 1 1 3 2 1 4 0 1 4 1 1 5 0 1 5 2 2 1 2 Value is limited to 0, 1, or 2. What I need to do is pivot/transform this data into a column-based count of how many times each possible Value appears, grouped by ID, ID1. The output of the above should be: ID ID1 Val0 Val1 Val2 1 1 1 0 0 1 2 0 2 0 1 3 0 1 1 1 4 1 1 0 1 5 1 0 1 2 1 0 0 1 I'm using SQL Server 2008. How do I do this?

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• Insert consecutive numbers

  - by Markus

  Hi. I have a table A (Acons, A1, A2, A3) in which I should insert information from another table B with columns (B1, B2, B3). The Acons is a column in which should contain some consecutive numbers (it is not an identity and I cannot make it identity). I know xmin - starting the from number the sequence has to be computed. How can I insert the rows into the table A, using a single Insert statement? I tried like the following, but it didn't work: DECLARE @i AS INT; SET @i = xmin; INSERT INTO A(Acons, A1, A2, A3) SELECT @i = (Bcons = (@i + 1)), B1, B2, B3 FROM B Unfortunatelly, the above solution does not work;

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• How do I select from a stored procedure in Sybase?

  - by Nick Fortescue

  My DBA has constructed me a stored procedure in a Sybase database, for which I don't have the definition. If I run it, it returns a resultset with a set of columns and values. I would like to SELECT further to reduce the rows in the result set. Is this possible? From this question it seems like I could insert the results into a temporary table, but I'm not sure I've got permissions to do this. Is there any way I can SELECT certain rows, or if not, can someone give me example code for simulating with a temporary table?

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• Rendering field data as a link in Ruby on Rails...

  - by bgadoci

  Ok, I think this is probably an easy question but for the life of my I can't figure it out. I have created a table called ugtags and in that table I have two columns (beyond the basics), 'name' and 'link'. I am trying to allow a user to add a link to a page. Ideally they would enter the link title (name) and the url (link) and in the view it would display the title as a link to the url that was entered in the link column. I there a way to do it by simply affecting the <%= link_to h(ugtag.name) %> code?

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• How can I neatly clean my R workspace while preserving certain objects?

  - by briandk

  Suppose I'm messing about with some data by binding vectors together, as I'm wont to do on a lazy sunday afternoon. x <- rnorm(25, mean = 65, sd = 10) y <- rnorm(25, mean = 75, sd = 7) z <- 1:25 dd <- data.frame(mscore = x, vscore = y, caseid = z) I've now got my new dataframe dd, which is wonderful. But there's also still the detritus from my prior slicings and dicings: > ls() [1] "dd" "x" "y" "z" What's a simple way to clean up my workspace if I no longer need my "source" columns, but I want to keep the dataframe? That is, now that I'm done manipulating data I'd like to just have dd and none of the smaller variables that might inadvertently mask further analysis: > ls() [1] "dd" I feel like the solution must be of the form rm(ls[ -(dd) ]) or something, but I can't quite figure out how to say "please clean up everything BUT the following objects."

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