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  • Ruby on Rails : How can i display data for the current view from a different table

    - by krishkule
    This might be a easy-to-answer question, but its a pain in the bum for me.... So... I have two tables - Chords - |id|chord|name|rating|artist_id| Artists - |id|artist| (the relations : chords : belongs_to :artist artists : has_many :chords ) And in the index page for "chords" i want to display chord,name,rating from Chords table AND artist from the Artists table this is the code for the chrod's index.html.erb : <table border="1"> <%@chords.each do |chord|%> <tr> <td><%=chord.artist.artist%></td> <td><%= link_to chord.name, chord %></td> <td><%=chord.rating%></td> <td><%= chord.created_at %></td> </tr> <%end%> </table> The error message is : undefined method `artist' for nil:NilClass Actually, at first it worked, but when i started to create the "new.html.erb" page and the create,new controllers, it stopped working - thats why this is so confusing for me! I will be glad to hear any critique and suggestions! Thank you

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  • how to generate the "create table" sql statement for an existing table in postgreSQL

    - by Raja
    I have a table created long ago in postgreSQL. Now i want to look at the sql statement used to create it but cannot figure it out. Also when i do the \dS+ tablename it says table not found, but \dt+ tablename is working fine. The \dS+ lists all the table names owned by the root postgres user and doesn't show up tables that i created with my user account. Any help is greatly appreciated. Thanks

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  • Counting in R data.table

    - by Simon Z.
    I have the following data.table set.seed(1) DT <- data.table(VAL = sample(c(1, 2, 3), 10, replace = TRUE)) VAL 1: 1 2: 2 3: 2 4: 3 5: 1 6: 3 7: 3 8: 2 9: 2 10: 1 Now I want to to perform two tasks: Count the occurrences of numbers in VAL. Count within all rows with the same value VAL (first, second, third occurrence) At the end I want the result VAL COUNT IDX 1: 1 3 1 2: 2 4 1 3: 2 4 2 4: 3 3 1 5: 1 3 2 6: 3 3 2 7: 3 3 3 8: 2 4 3 9: 2 4 4 10: 1 3 3 where COUNT defines task 1. and IDX task 2. I tried to work with which and length using .I: dt[, list(COUNT = length(VAL == VAL[.I]), IDX = which(which(VAL == VAL[.I]) == .I))] but this does not work as .I refers to a vector with the index, so I guess one must use .I[]. Though inside .I[] I again face the problem, that I do not have the row index and I do know (from reading data.table FAQ and following the posts here) that looping through rows should be avoided if possible. So, what's the data.table way?

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  • Placeholder containing dynamic table is empty unless I create table twice

    - by Mike O.
    I am dynamically creating a table that contains a textbox in each cell. The table is put in a placeholder control. Everything displays perfectly. The problem is when I go to retrieve the values entered in the cells. I have the code to generate the table in a separate method called CreateTable(). In order for my program to find a table in the placeholder when I go to save, I have to run CreateTable() in a postback event AND in the PageLoad event. If I call CreateTable() in only one of those places and I try to save, it says the placeholder is empty and, therefore, I cannot save the textbox contents. I've tried calling CreateTable() from InitLoad but that doesn't work because it needs to reference values from three static controls: 1 dropdown, 1 listbox, and 1 calendar control, which I don't believe have had their viewstate rendered yet. Anyone have any ideas? It would sure be nice not to have to double the number of database calls just to make this work.

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  • SQL - table alias scope.

    - by Support - multilanguage SO
    I've just learned ( yesterday ) to use "exists" instead of "in". BAD select * from table where nameid in ( select nameid from othertable where otherdesc = 'SomeDesc' ) GOOD select * from table t where exists ( select nameid from othertable o where t.nameid = o.nameid and otherdesc = 'SomeDesc' ) And I have some questions about this: 1) The explanation as I understood was: "The reason why this is better is because only the matching values will be returned instead of building a massive list of possible results". Does that mean that while the first subquery might return 900 results the second will return only 1 ( yes or no )? 2) In the past I have had the RDBMS complainin: "only the first 1000 rows might be retrieved", this second approach would solve that problem? 3) What is the scope of the alias in the second subquery?... does the alias only lives in the parenthesis? for example select * from table t where exists ( select nameid from othertable o where t.nameid = o.nameid and otherdesc = 'SomeDesc' ) AND select nameid from othertable o where t.nameid = o.nameid and otherdesc = 'SomeOtherDesc' ) That is, if I use the same alias ( o for table othertable ) In the second "exist" will it present any problem with the first exists? or are they totally independent? Is this something Oracle only related or it is valid for most RDBMS? Thanks a lot

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  • Should I learn two (or more) programming languages in parallel?

    - by c_maker
    I found entries on this site about learning a new programming language, however, I have not come across anything that talks about the advantages and disadvantages of learning two languages at the same time. Let's say my goal is to learn two new languages in a year. I understand that the definition of learning a new language is different for everyone and you can probably never know everything about a language. I believe in most cases the following things are enough to include the language in your resume and say that you are proficient in it (list is not in any particular order): Know its syntax so you can write a simple program in it Compare its underlying concepts with concepts of other languages Know best practices Know what libraries are available Know in what situations to use it Understand the flow of a more complex program At least know most of what you do not know I would probably look for a good book and pick an open source project for both of these languages to start with. My questions: Is it best to spend 5 months learning language#1 then 5 months learning language#2, or should you mix the two. Mixing them I mean you work on them in parallel. Should you pick two languages that are similar or different? Are there any advantages/disadvantages of let's say learning Lisp in tandem with Ruby? Is it a good idea to pick two languages with similar syntax or would it be too confusing? Please tell me what your experiences are regarding this. Does it make a difference if you are a beginner or a senior programmer?

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  • Altering sql tables based on condition

    - by Parker
    Is there any possible way to add a row of data to only some of the tables in a database? I am not sure what parameter I could use amongst the tables to compare them to each other. Any Ideas? For Example: My database has tables that are (let's say) group A tables, and tables that are group B. I want to add a row to only the group B tables while leaving the group A tables untouched. Sorry I should have been a bit more specific. The tables that need to have a row added will change. My application monitors inventory in different store locations(each table in my database represents a store). When I need to add an item to inventory(the items are rows in the tables) I don't want to have to manually add the row to all the store tables. My problem is: Not all the tables in the database represent stores. For instance one table stores the user login data. Obviously I do not want to add the new row to this table. How do I update only the tables that represent stores?

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  • How do I execute a sql statement through a variable (dyname sql) that tries to do an insert into a variable table?

    - by Testifier
    If I do what I wanna do with a TEMPORARY TABLE, it works fine: DECLARE @CTRFR VARCHAR(MAX) SET @CTRFR = 'select blah blah blah' -- <-- very long select statement. this returns a 0 or some greater number. Please note! --> I NEED THIS NUMBER. IF EXISTS ( SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo][#CTRFRResult]') AND type IN ( N'U' ) ) DROP TABLE [dbo].[#CTRFRResult] CREATE TABLE #CTRFRResult ( CTRFRResult VARCHAR(MAX) ) SET @CTRFR = 'insert into #CTRFRResult ' + @CTRFR EXEC(@CTRFR) The above works fine. The problem is that several databases are using the same TEMP table. Therefore I need to use a VARIABLE table (instead of a temporary table). What I have below is not working because it says that the table must be declared. DECLARE @CTRFRResult TABLE ( CTRFRResult VARCHAR(MAX) ) SET @CTRFR = 'insert into @CTRFRResult ' + @CTRFR -- I think the issue is here. EXEC(@CTRFR) Setting @CTRFR to 'insert into...' is not working because I'm assuming the table name is out of scope. How would I go about mimicking the temporary table code using a variable table?

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  • PHP while loop, table row

    - by Elliott
    Hi, I'm trying to loop through a database and output data into a div, if there are 3 divs horizontally accross it will the start a new tr until it reaches another 3 etc. It is currently outputted like : [] [] [] [] [] [] Currently I have it working when it reaches 3 it starts a new row, but I don't know how I can only echo a new tr once? As it creates a new table row each time. echo '<table><tr>'; while ($result) { $i ++; if ($i&3) { echo '<td> <div>Row Data</div> </td>'; } else { echo '<tr> <td> <div>Row Data</div> </td></tr>'; } } echo '</tr></table>'; The $result variable is the recordset from my sql query, everything works fine I just don't know how to only create a new table row once? Thanks

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  • Using data.table to aggregate

    - by dayne
    After multiple suggestions from SO users, I am finally trying to convert my code over to using data.tables. library(data.table) DT <- data.table(plate = paste0("plate",rep(1:2,each=5)), id = rep(c("CTRL","CTRL","ID1","ID2","ID3"),2), val = 1:10) > DT plate id val 1: plate1 CTRL 1 2: plate1 CTRL 2 3: plate1 ID1 3 4: plate1 ID2 4 5: plate1 ID3 5 6: plate2 CTRL 6 7: plate2 CTRL 7 8: plate2 ID1 8 9: plate2 ID2 9 10: plate2 ID3 10 What I would like to do is take the average of DT[,val] by plate when the id is "CTRL". I would normally aggregate the data frame, then use match to map the values back to a new column, 'ctrl'. Using the data.table package I can get: DT[id=="CTRL",ctrl:=mean(val),by=plate] > DT plate id val ctrl 1: plate1 CTRL 1 1.5 2: plate1 CTRL 2 1.5 3: plate1 ID1 3 NA 4: plate1 ID2 4 NA 5: plate1 ID3 5 NA 6: plate2 CTRL 6 6.5 7: plate2 CTRL 7 6.5 8: plate2 ID1 8 NA 9: plate2 ID2 9 NA 10: plate2 ID3 10 NA What I need is really: DT <- data.table(plate = paste0("plate",rep(1:2,each=5)), id = rep(c("CTRL","CTRL","ID1","ID2","ID3"),2), val = 1:10, ctrl = rep(c(1.5,6.5),each=5)) > DT plate id val ctrl 1: plate1 CTRL 1 1.5 2: plate1 CTRL 2 1.5 3: plate1 ID1 3 1.5 4: plate1 ID2 4 1.5 5: plate1 ID3 5 1.5 6: plate2 CTRL 6 6.5 7: plate2 CTRL 7 6.5 8: plate2 ID1 8 6.5 9: plate2 ID2 9 6.5 10: plate2 ID3 10 6.5 Eventually I would like to use much more complicated selections of the values, but I do not know how to select specific values, run some function, then map those values back to the appropriate row using data frames.

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  • wordpress.com to self-hosted wordpress blog

    - by sAc
    Hello, I have been writing articles on the wordpress.com blog, now i am looking to move it to self-hosted wordpress blog but i wonder: 1) Should i move all my articles on the new blog or just put an article on my last blog that more articles will be posted on my new blog? 2) If i move all articles on my new blog, i am not sure about how google will react to it because there are articles with good number of visitors, won't this be seo-un-friendly because i am not sure but google will re-create page reputation stuff, etc or those articles will have same popularity even if i move elsewhere? 3) What are the implications and side-effects in moving from wordpress.com blog to self-hosted wordpress blog? Thanks

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  • Is your test method self-validating ?

    - by mehfuzh
    Writing state of art unit tests that can validate your every part of the framework is challenging and interesting at the same time, its like becoming a samurai. One of the key concept in this is to keep our test synced all the time as underlying code changes and thus breaking them to the furthest unit as possible.  This also means, we should avoid  multiple conditions embedded in a single test. Let’s consider the following example of transfer funds. [Fact] public void ShouldAssertTranserFunds() {     var currencyService = Mock.Create<ICurrencyService>();     //// current rate     Mock.Arrange(() => currencyService.GetConversionRate("AUS", "CAD")).Returns(0.88f);       Account to = new Account { Currency = "AUS", Balance = 120 };     Account from = new Account { Currency = "CAD" };       AccountService accService = new AccountService(currencyService);       Assert.Throws<InvalidOperationException>(() => accService.TranferFunds(to, from, 200f));       accService.TranferFunds(to, from, 100f);       Assert.Equal(from.Balance, 88);     Assert.Equal(20, to.Balance); } At first look,  it seems ok but as you look more closely , it is actually doing two tasks in one test. At line# 10 it is trying to validate the exception for invalid fund transfer and finally it is asserting if the currency conversion is successfully made. Here, the name of the test itself is pretty vague. The first rule for writing unit test should always reflect to inner working of the target code, where just by looking at their names it is self explanatory. Having a obscure name for a test method not only increase the chances of cluttering the test code, but it also gives the opportunity to add multiple paths into it and eventually makes things messy as possible. I would rater have two test methods that explicitly describes its intent and are more self-validating. ShouldThrowExceptionForInvalidTransferOperation ShouldAssertTransferForExpectedConversionRate Having, this type of breakdown also helps us pin-point reported bugs easily rather wasting any time on debugging for something more general and can minimize confusion among team members. Finally, we should always make our test F.I.R.S.T ( Fast.Independent.Repeatable.Self-validating.Timely) [ Bob martin – Clean Code]. Only this will be enough to ensure, our test is as simple and clean as possible.   Hope that helps

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  • How Curiosity Took Its Self Portrait [Video]

    - by Jason Fitzpatrick
    There was enough confusion among the public as to how exactly the Curiosity Rover was able to photograph itself without the camera arm intruding into the photo that NASA released this video detailing the process. For those readers familiar with photograph blending and stitching using multiple photo sources, this should come as no surprise. For the unfamiliar, it’s an interesting look at how dozens of photos can be blended together so effectively that the arm–robotic or otherwise–of the photographer can be taken right out. Hit up the link below to read more about how NASA practiced on Earth for the shot and to see a high-res copy of the actual self portrait. Mars Rover Self-Portrait Shoot Uses Arm Choreography [NASA] Secure Yourself by Using Two-Step Verification on These 16 Web Services How to Fix a Stuck Pixel on an LCD Monitor How to Factory Reset Your Android Phone or Tablet When It Won’t Boot

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  • SQL SERVER – How to an Add Identity Column to Table in SQL Server

    - by Pinal Dave
    Here is the question I received on SQLAuthority Fan Page. “How do I add an identity column to Table in SQL Server? “ Sometime the questions are very very simple but the answer is not easy to find. Scenario 1: If you are table does not have identity column, you can simply add the identity column by executing following script: ALTER TABLE MyTable ADD ID INT IDENTITY(1,1) NOT NULL Scenario 2: If your table already has a column which you want to convert to identity column, you can’t do that directly. There is a workaround for the same which I have discussed in depth over the article Add or Remove Identity Property on Column. Scenario 3: If your table has already identity column and you can want to add another identity column for any reason – that is not possible. A table can have only one identity column. If you try to have multiple identity column your table, it will give following error. Msg 2744, Level 16, State 2, Line 2 Multiple identity columns specified for table ‘MyTable‘. Only one identity column per table is allowed. Leave a comment if you have any suggestion. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Identity

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  • Self Documenting Code Vs. Commented Code

    - by Phill
    I had a search but didn't find what I was looking for, please feel free to link me if this question has already being asked. Earlier this month this post was made: http://net.tutsplus.com/tutorials/php/why-youre-a-bad-php-programmer/ Basically to sum it up, you're a bad programmer if you don't write comments. My personal opinion is that code should be descriptive and mostly not require comment's unless the code cannot be self describing. In the example given // Get the extension off the image filename $pieces = explode('.', $image_name); $extension = array_pop($pieces); The author said this code should be given a comment, my personal opinion is the code should be a function call that is descriptive: $extension = GetFileExtension($image_filename); However in the comments someone actually made just that suggestion: http://net.tutsplus.com/tutorials/php/why-youre-a-bad-php-programmer/comment-page-2/#comment-357130 The author responded by saying the commenter was "one of those people", i.e, a bad programmer. What are everyone elses views on Self Describing Code vs Commenting Code?

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  • Self-Service Testing Cloud Enables Improved Efficiency and Productivity for Development and Quality Assurance Organizations

    - by Sandra Cheevers
    With organizations spending as much as 50 percent of their QA time with non-test related activities like setting up hardware and deploying applications and test tools, the cloud will bring obvious benefits. Oracle announced today self-service testing capabilities to enable you to deploy private or public testing clouds. These capabilities help software development and QA organizations deliver higher quality applications, while enhancing testing efficiency and reducing duration of testing projects. This kind of cloud based self-service testing provides better efficiency and agility. The Testing-as-a-Service solution offers test lab management, automatic deployment of complex multi-tier applications, rich application performance monitoring, test data management and chargeback, all in a unified workflow. For more details, read the press release Oracle Announces Oracle Enterprise Manager 12c Testing-as-a-Service Solution here.

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  • Introduction to Microsoft SQL Azure: Free self-paced Microsoft class

    - by Jim Duffy
    Here is a wonderful opportunity to take advantage of some FREE Microsoft Learning content on SQL Azure. This self-paced 2 hour class is broken down into 4 segments each with a self test at the end. Class Segments 1) Understanding the SQL Azure Platform 2) Designing Applications for SQL Azure 3) Migrating Applications to SQL Azure 4) Achieving Scale with SQL Azure If you’re getting started with Windows Azure or have been working with it for a while and need to take advantage of the storage capabilities offered by SQL Azure this is going to be a great place for you to start learning. Have a day. :-|

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  • Mixing self signed certs with traditional SSL

    - by brentonstrine
    I have a traditional SSL cert going to a subdomain secure.mydomain.com on my domain. My host required me to have a dedicated IP in order to do this. I would also like to use HTTPS on my site for when I log into WordPress, etc. and since this is just for me, I don't mind self signing it and clicking through the scary messages. Is there a way to use a self signed cert for mydomain.com/wp-admin (just for me) when I already am on a dedicated IP that already has a traditional SSL cert for normal users on secure.mydomain.com? (FWIW, I'm on WHM without root access.)

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  • Self-documenting code vs Javadocs?

    - by Andiaz
    Recently I've been working on refactoring parts of the code base I'm currently dealing with - not only to understand it better myself, but also to make it easier for others who are working on the code. I tend to lean on the side of thinking that self-documenting code is nice. I just think it's cleaner and if the code speaks for itself, well... That's great. On the other hand we have documentation such as javadocs. I like this as well, but there's a certain risk that comments here gets outdated (as well as comments in general of course). However, if they are up-to-date they can be extremely useful of say, understanding a complex algorithm. What are the best practices for this? Where do you draw the line between self-documenting code and javadocs?

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  • Now Available:Oracle Utilities Customer Self Service Version 2.1

    - by Roxana Babiciu
    The Oracle Utilities Global Business Unit is pleased to announce the general availability of Oracle Utilities Customer Self Service 2.1. It is ready for customers and partners to download and install via the Oracle Software Delivery Cloud. Key Features & Benefits: Oracle Utilities Customer Self Service 2.1 includes several new capabilities and enhancements including significantly improved Commercial Account Management and Advanced Notification Management using a new Oracle Utilities Notification Center module (licensed separately). These include the following: Advanced Notification Management Online Issues and Forms Management • Budget Management and Billing for Billed Budgets Prepaid User Dashboard Enhanced Usage Details Web Presentment Start/Stop/Transfer Service Automation Payment Arrangement Automation Account Sets Management for Large Commercial Customers Multiple Account Usage Data Aggregation, Comparison, and Data Download Multiple Account Financial History Mobile Outage Maps More information can be found on OPN

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  • Hibernate: Parent/Child relationship in a single-table

    - by Dee
    I hardly see any pointer on the following problem related to Hibernate. This pertains to implementing inheritance using a single database table with a parent-child relationship to itself. For example: CREATE TABLE Employee ( empId BIGINT NOT NULL AUTO_INCREMENT, empName VARCHAR(100) NOT NULL, managerId BIGINT, CONSTRAINT pk_employee PRIMARY KEY (empId) ) Here, the managerId column may be null, or may point to another row of the Employee table. Business rule requires the Employee to know about all his reportees and for him to know about his/her manager. The business rules also allow rows to have null managerId (the CEO of the organisation doesn't have a manager). How do we map this relationship in Hibernate, standard many-to-one relationship doesn't work here? Example code would be appreciated.

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  • Hibernate: Parent/Child relationship in a single-table

    - by Dee
    I hardly see any pointer on the following problem related to Hibernate. This pertains to implementing inheritance using a single database table with a parent-child relationship to itself. For example: CREATE TABLE Employee ( empId BIGINT NOT NULL AUTO_INCREMENT, empName VARCHAR(100) NOT NULL, managerId BIGINT, CONSTRAINT pk_employee PRIMARY KEY (empId) ) Here, the managerId column may be null, or may point to another row of the Employee table. Business rule requires the Employee to know about all his reportees and for him to know about his/her manager. The business rules also allow rows to have null managerId (the CEO of the organisation doesn't have a manager). How do we map this relationship in Hibernate, standard many-to-one relationship doesn't work here? Example code would be appreciated.

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  • Gap after table in LaTex

    - by Tim
    Hi, I notice that there is some gap after my table. See the following snapshot: http://i42.tinypic.com/23rkdn6.jpg My Latex code is: \begin{table}[htb] \caption{Error rates VS training size in AdaBoosted stump, SVM and kNN. \label{tab:examplecount8000errerrplot}} \begin{center} \begin{tabular}{c c} \includegraphics[scale=0.4]{../boost.eps} & \includegraphics[scale=0.4]{../svm.eps} \\ \includegraphics[scale=0.4]{../knn.eps} & \\ \end{tabular} \end{center} \end{table} % \subsection{Feature Numbers} Is the gap normal or How can I reduce the gap to be normal? Thanks and regards!

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