dataset

问题 This question already has answers here : Extracting specific columns from a data frame (10 answers) Closed 3 years ago . I have a data frame in R that consists of around 400 variables (as columns), though I only need 25 of them. While I know how to delete specific columns, because of the impracticality of deleting 375 variables - is there any method in which I could delete all of them, except the specified 25 by using the variable's string name? Thanks. 回答1: Sample example: df <- data.frame(a

问题 I need to merge two data sets that have no common variable, and only one variable apiece. One data set is about 200 lines of unique values and the other is 80,000 unique lines. I have tried the common merges, but cannot get what I'm looking for. The following is what I'm after: Set a variables: x y Set b variables: 1 2 3 Desired merged data sets result (2 columns): x 1 x 2 x 3 y 1 y 2 y 3 Thanks for any insight. 回答1: From my understanding of your question, it seems like you're trying to do a

问题 Dim strText As String = tbRefine.Text Dim sql As String = "SELECT user_name,forename,surname,game_cash,reg_group FROM tblGame WHERE user_name LIKE '" + strSearchText + "' & '*'" Dim dsRefine As New DataSet GetDataset(sql, "tblGame", dsRefine) MsgBox(dsRefine.Tables("tblGame").Rows(0).Item(2).ToString) This is not working, it crashes and says there is nothing in the dataset. I know the dataset function works as its worked successfully before. When i print out the sql statement into microsoft

问题 I know this question has been asked a hundred of times and I have looked at them all and don't know what's going wrong. This is the table in access: tbl_Slip SlipNo*, EmpID, ScaleID, Month-Year, RaiseBasic, OtherDed, Tax, Arrears, Notes, all the fields are integer type except for Month-Year and Notes which are text. Now the C# Part: This is the code I use. I tried to find out the error so made a button with harcoded values. (The oledbConnection works fine. I use it to display data on the form

问题 I faced a problem when trying to access row again. I have TreeView component and in Tag property I put row from datatable: foreach (DataRow row in catalogDataSet.category) { if (row["parent"].ToString().Equals("0")) { TreeNode node = new TreeNode(); node.Text = row["name"].ToString(); node.Tag = row; string nodeId = row["id"].ToString(); if (this.HasChilds(nodeId)) { this.fillChilds(nodeId, node); } tree.Nodes.Add(node); } } Then I try to access row`s id: int locationId = int.Parse(((DataRow

问题 I've got a typed DataSet with multiple tables that I want copy, complete with data as well as schema. I can access the tables like so in my original: MyDataSetType dsMyFirstDataSet; MyDataTableType dtTable1; MyDataTableType dtTable2; dtTable1 = dsMyFirstDataSet.MeaningfulTableName1; dtTable2 = dsMyFirstDataSet.MeaningfulTableName2; When I do the following, I can no longer access the tables via the names in the new version but I can via the Tables collection. MyDataSetType dsMySecondDataSet;

问题 I've got XML that describes certain data (a template) that I want to be able to edit. I load XML into DataSet (see fig. 1 below), plug DataSet tables into DataGridView (switch between them using a separate comboBox), make changes and then save XML (simple DataSet.WriteXML directive). The XML I read looks very nice and humanly readable (see fig. 2 below), however, the written XML is nowhere near the original (see fig. 3 below). My goal is to allow editing of XML document and preserve it in the

问题 Am using a DataSet and a TableAdapter to populate a Datagridview. The Datagridview allows inserting new records at the bottom. Now when I enter values for the new record in the Datagridview, the record is not automatically saved back to the database. Which event do U need to handle or what code do I need to write to get the new record saved back to the databse. am using C#. 回答1: Are you calling the Update() method on the TableAdapter ? The following code comes from MSDN's discussion on the

问题 I have Crystal reports in my project that is designed using a data set (Having table with column name inLanguage1, inLanguage2). This data set is filled with data from one of the tables from a database, each table have two columns that store names in two different languages. Eg: Table 1 has name in Hindi and English. Table 2 has name in English and Hindi. Table 3 has name in Kannada and Hindi. While I store names in these tables, using my frontend (C#), I have set the corresponding font type

问题 I want to write a query here https://lod4all.net/sparql.html that finds all the classes associated with a given word. how can I do? 来源： https://stackoverflow.com/questions/48771595/how-to-find-classes-associated-given-word-sparql