Datatable columns add

Datatable columns add DEFAULT

Adding Columns to a DataTable

A DataTable contains a collection of DataColumn objects referenced by the Columns property of the table. This collection of columns, along with any constraints, defines the schema, or structure, of the table.

You create DataColumn objects within a table by using the DataColumn constructor, or by calling the Add method of the Columns property of the table, which is a DataColumnCollection. The Add method accepts optional ColumnName, DataType, and Expression arguments and creates a new DataColumn as a member of the collection. It also accepts an existing DataColumn object and adds it to the collection, and returns a reference to the added DataColumn if requested. Because DataTable objects are not specific to any data source, .NET Framework types are used when specifying the data type of a DataColumn.

The following example adds four columns to a DataTable.

In the example, notice that the properties for the CustID column are set to not allow DBNull values and to constrain values to be unique. However, if you define the CustID column as the primary key column of the table, the AllowDBNull property will automatically be set to false and the Unique property will automatically be set to true. For more information, see Defining Primary Keys.

Caution

If a column name is not supplied for a column, the column is given an incremental default name of ColumnN, starting with "Column1", when it is added to the DataColumnCollection. We recommend that you avoid the naming convention of "ColumnN" when you supply a column name, because the name you supply may conflict with an existing default column name in the DataColumnCollection. If the supplied name already exists, an exception is thrown.

If you are using XElement as the DataType of a DataColumn in the DataTable, XML serialization will not work when you read in data. For example, if you write out a XmlDocument by using the method, upon serialization to XML there is an additional parent node in the XElement. To work around this problem, use the SqlXml type instead of XElement. and work correctly with SqlXml.

See also

Sours: https://docs.microsoft.com/en-us/dotnet/framework/data/adonet/dataset-datatable-dataview/adding-columns-to-a-datatable

C# DataTable ExamplesStore data in memory with a DataTable. Add rows, call Compute and Merge, and set PrimaryKey.

DataTable. This class stores rows and columns of data. In C# we can address parts of the DataTable with DataRow and DataColumn. And a DataSet can contain multiple tables.

Data collection.DataTable is part of the System.Data namespace. We add, select and iterate over stored data. The foreach-loop can be used on the Rows in a DataTable.

DataTable Select

DataTable foreach

First example.A key advantage to DataTable is it allows database-like manipulations of data (even simple joins). But before these advanced features can be used, we must create a table.

Step 1 We call GetTable, which generates a table. The returned object could be persisted to disk, displayed, or stored in memory.

Step 2 We create a new DataTable reference. Then we add 4 columns—these include a type, specified with typeof.

Typeof, nameof

Step 3 We add the actual data as rows. The 4 arguments to each Add() call match up with the 4 columns already added.

Step 4 We print a cell value from the first row (row 0) and the Dosage column (which is an int).

C# program that uses DataTable

using System; using System.Data; class Program { static void Main() { // Step 1: get the DataTable.DataTabletable = GetTable(); // Step 4: print the first cell.Console.WriteLine("FIRST ROW, DOSAGE: {0}", table.Rows[0]["Dosage"]); } static DataTable GetTable() { // Step 2: here we create a DataTable.// We add 4 columns, each with a Type.DataTabletable = new DataTable(); table.Columns.Add("Dosage", typeof(int)); table.Columns.Add("Drug", typeof(string)); table.Columns.Add("Diagnosis", typeof(string)); table.Columns.Add("Date", typeof(DateTime)); // Step 3: here we add rows.table.Rows.Add(25, "Drug A", "Disease A", DateTime.Now); table.Rows.Add(50, "Drug Z", "Problem Z", DateTime.Now); table.Rows.Add(10, "Drug Q", "Disorder Q", DateTime.Now); table.Rows.Add(21, "Medicine A", "Diagnosis A", DateTime.Now); return table; } }FIRST ROW, DOSAGE: 25
Rows, field.We build in complexity—here we loop over all Rows of our DataTable. We then access the first field, with the Field extension method, as an int.

Generic method Field is a generic method. So we must specify its parametric type (here, int) to indicate its behavior.

DataRow Field

Rows Often we must access the rows of a DataTable. The Rows property, which can be looped over, is ideal here.

C# program that uses Rows, Field

using System; using System.Data; class Program { static void Main() { // This uses the GetTable method (please paste it in).DataTable data = GetTable(); // Loop over all rows.foreach (DataRow row in data.Rows) { // Write value of first field as integer.Console.WriteLine(row.Field<int>(0)); } } }25 50 10 21
DataGridView example.We insert data from object collections (like List) into DataTable. We then render that table to the screen with Windows Forms. DataTable helps display data.

DataGridView

Form This code is a Form and can be placed in a Windows Forms application with a DataGridView. It creates a DataTable.

Arrays The 2 arrays are initialized in the class and constructor. They contain column information.

Add We add the column names to our DataTable with Columns.Add. These are the column headers.

Tip DataTable requires objects to assign to the cells. Objects can hold any type of data.

Object

C# program that uses DataGridView

using System.Collections.Generic; using System.Data; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { /// <summary> /// Contains column names. /// </summary>List<string> _names = new List<string>(); /// <summary> /// Contains column data arrays. /// </summary>List<double[]> _dataArray = new List<double[]>(); public Form1() { InitializeComponent(); // Example column._names.Add("Cat"); // Three numbers of cat data._dataArray.Add(new double[] { , , }); // Another example column._names.Add("Dog"); // Add three numbers of dog data._dataArray.Add(new double[] { , , }); // Render the DataGridView.dataGridView1.DataSource = GetResultsTable(); } /// <summary> /// This method builds a DataTable of the data. /// </summary>public DataTable GetResultsTable() { // Create the output table.DataTabled = new DataTable(); // Loop through all process names.for (int i = 0; i < this._dataArray.Count; i++) { // The current process name.string name = this._names[i]; // Add the program name to our columns.d.Columns.Add(name); // Add all of the memory numbers to an object list.List<object> objectNumbers = new List<object>(); // Put every column's numbers in this List.foreach (double number in this._dataArray[i]) { objectNumbers.Add((object)number); } // Keep adding rows until we have enough.while (d.Rows.Count < objectNumbers.Count) { d.Rows.Add(); } // Add each item to the cells in the column.for (int a = 0; a < objectNumbers.Count; a++) { d.Rows[a][i] = objectNumbers[a]; } } return d; } } }
Using.DataTable can be placed in a using statement. This can help programs performance. Often the using block construct helps improve resource management.

Tip We can add Columns and Rows to the DataTable instance inside (but not outside) the using block.

Tip 2 In this example, the Dispose method is invoked. After the using statement, Dispose() on DataTable is called.

Using

Dispose When Dispose is called, native resources are released. This may help resource usage problems.

C# program that uses using statement

using System; using System.Data; class Program { static void Main() { // Safely create and dispose of a DataTable.using(DataTable table = new DataTable()) { // Two columns.table.Columns.Add("Name", typeof(string)); table.Columns.Add("Date", typeof(DateTime)); // Add two rows.table.Rows.Add("cat", DateTime.Now); table.Rows.Add("dog", DateTime.Today); // Display first field.Console.WriteLine(table.Rows[0].Field<string>(0)); } } }cat
Compute.We can use the Compute() method with SUM to sum a column in a DataTable. Here we create a product data table, and add 2 rows to it.

And We call Compute() with a SUM of the column name (like Variety1). The filter argument can be specified as string.Empty.

Result The Total row has the columns summed correctly. We do not need to sum the values with a for-loop.

C# program that uses Compute, SUM expression

using System; using System.Data; class Program { static void Main() { var table = new DataTable(); table.Columns.Add("Product", typeof(string)); table.Columns.Add("Variety1", typeof(decimal)); table.Columns.Add("Variety2", typeof(decimal)); table.Columns.Add("Variety3", typeof(decimal)); table.Columns.Add("Variety4", typeof(decimal)); table.Rows.Add("Product 1", 10, 12, 14, 45); table.Rows.Add("Product 2", 20, 15, 24, 0); // Use Compute and SUM to sum up columns.// Use string.Empty as the filter as it is not needed.var sum1 = (decimal)table.Compute("SUM(Variety1)", string.Empty); var sum2 = (decimal)table.Compute("SUM(Variety2)", string.Empty); var sum3 = (decimal)table.Compute("SUM(Variety3)", string.Empty); var sum4 = (decimal)table.Compute("SUM(Variety4)", string.Empty); table.Rows.Add("Total", sum1, sum2, sum3, sum4); // Loop over rows.foreach(DataRow row in table.Rows) { Console.WriteLine(":: ROW ::"); foreach(var item in row.ItemArray) { Console.WriteLine(item); } } } }:: ROW :: Product 1 10 12 14 45 :: ROW :: Product 2 20 15 24 0 :: ROW :: Total 30 27 38 45
Merge, PrimaryKey.We can join 2 DataTables together—each resulting row in the DataTable will contain all data from each table for the key. We must set a PrimaryKey column to use Merge.

Here We create 2 DataTables with names PictureStyle and PictureSize. Each table has a column of IDs, and these IDs match in each table.

PrimaryKey We assign the PrimaryKey to a column (or array of columns). Here we use the ID column, so we can join on the IDs.

Merge We invoke Merge() to join the 2 tables based on their PrimaryKeys. One or more columns can be used.

Result The "PictureStyle" DataTable is updated to include the row fields from the "PictureSize" data table—each row now has 3 cells.

C# program that uses Merge to join DataTables

using System; using System.Data; class Program { static void Main() { // Create 1 table, setting ID as PrimaryKey.DataTabletableStyle = new DataTable("PictureStyle"); var idColumn = new DataColumn("ID", typeof(int)); tableStyle.Columns.Add(idColumn); tableStyle.PrimaryKey= new DataColumn[] { idColumn }; tableStyle.Columns.Add(new DataColumn("Style", typeof(string))); tableStyle.Rows.Add(1, "vertical"); tableStyle.Rows.Add(2, "square"); tableStyle.Rows.Add(3, "panorama"); Display(tableStyle); // Create a second table, also using ID for PrimaryKey.DataTabletableSize = new DataTable("PictureSize"); var idColumnSize = new DataColumn("ID", typeof(int)); tableSize.Columns.Add(idColumnSize); tableSize.PrimaryKey= new DataColumn[] { idColumnSize }; tableSize.Columns.Add(new DataColumn("Size", typeof(int))); tableSize.Rows.Add(1, 50); tableSize.Rows.Add(2, ); tableSize.Rows.Add(3, ); Display(tableSize); // Merge the 2 tables together based on the PrimaryKey.tableStyle.Merge(tableSize); Display(tableStyle); } static void Display(DataTable table) { // Display merged table.Console.WriteLine("::TABLE::"); foreach (DataRow row in table.Rows) { Console.WriteLine("ROW: {0}", string.Join(",", row.ItemArray)); } } }::TABLE:: ROW: 1,vertical ROW: 2,square ROW: 3,panorama ::TABLE:: ROW: 1,50 ROW: 2, ROW: 3, ::TABLE:: ROW: 1,vertical,50ROW: 2,square,ROW: 3,panorama,
System.Data objects.Each DataTable has DataColumn and DataRow parts. And with DataSet and DataView we can collect 2 or more DataTables, or filter data.

DataColumn

DataRow

DataSet

DataView

Foreach.Often we want to loop over our DataTable rows. This can be done with a foreach-loop. The exact syntax can be confusing, and objects are sometimes needed.

DataTable foreach

Compare rows.Data may sometimes contain duplicate rows. This condition can be detected with a simple looping algorithm. The syntax can be used for many DataTable tasks.

DataTable Compare Rows

Select.We can use the Select method on DataTable. This filters elements based on some criteria. We receive an array of DataRow instances that match our filter.

DataTable Select

DataSource.With this property in Windows Forms, we can assign a DataTable to render the data. DataSource improves display performance. Everything is added at once.

DataSource

Convert.The List type is often useful. DataTable is better when we interact with controls such as DataGridView or with SQL databases. We can convert between the types.

Convert List, DataTable

RowChanged.A DataTable can monitor its changes. We use the RowChanged event, and similar events like ColumnChanged to detect changes. The AcceptChanges method too is helpful.

DataTable RowChanged

A summary. DataTable is a powerful, convenient class. We added columns. We added rows. DataTable is faster, in Windows Forms, than manually adding rows. It reduces complexity.

© sam allen. see site info on the changelog

Sours: https://www.dotnetperls.com/datatable
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sum()

Sum the values in a data set.

Fairly simply, this plug-in will take the data from an API result set and sum it, returning the summed value. The data can come from any data source, including column data, cells or rows.

Note that it will attempt to 'deformat' any string based data that is passed into it - i.e. it will strip any non-numeric characters in order to make a best effort attempt to sum all data types. This can be useful when working with formatting numbers such as currency. However the trade-off is that no error is thrown if non-numeric data is passed in. You should be aware of this in case unexpected values are returned - likely the input data is not what is expected.

Plug-in code

CDN

This plug-in is available on the DataTables CDN:

JS

Note that if you are using multiple plug-ins, it is beneficial in terms of performance to combine the plug-ins into a single file and host it on your own server, rather than making multiple requests to the DataTables CDN.

Version control

If you have any ideas for how this plug-in can be improved, or spot anything that is in error, it is available on GitHub and pull requests are very welcome!

Examples

Sours: https://datatables.net/plug-ins/api/sum()
Add Data Column in UiPath - UiPath Add Data Column Example - ExpoHub

C# program that uses DataColumn

using System; using System.Data; class Program { static void Main() { // // Construct the DataTable. //DataTable table = GetTable(); // // Loop over the column headers in the DataTable. //foreach(DataColumncolumn in table.Columns) { Console.WriteLine("{0} = {1}", column, column.DataType); } } /// <summary> /// Generates a DataTable with four columns. /// </summary>static DataTable GetTable() { // // Here we create a DataTable and add columns to it. //DataTable table = new DataTable(); table.Columns.Add("Dosage", typeof(int)); table.Columns.Add("Medication", typeof(string)); table.Columns.Add("Patient", typeof(string)); // // Add another column to the data table in a different way. //DataColumn column = new DataColumn("Appointment", typeof(DateTime)); table.Columns.Add(column); // // Here we add some DataRows. // Note that the row parameters must match the order and types of the columns. //table.Rows.Add(21, "Combivent", "Janet", DateTime.Now); table.Rows.Add(, "Dilantin", "Melanie", DateTime.Now); return table; } }Dosage = System.Int32 Medication = System.String Patient = System.String Appointment = System.DateTime

A summary. We looked at the DataColumn class. This type acts as a template for the in-memory relational database abstraction specified by the DataTable type.

© sam allen. see site info on the changelog

Sours: https://www.dotnetperls.com/datacolumn

Add datatable columns

Add rows

New rows can be added to a DataTable using the API method. Simply call the API function with the data for the new row (be it an array or object). Multiple rows can be added using the method (note the plural). Data can likewise be updated with the and methods.

Note that in order to see the new row in the table you must call the method, which is easily done through the chaining that the DataTables API employs.

This example shows a single row being added each time the button below is clicked upon.

The Editor extension adds full table editing controls to a DataTable, including creating, editing and deleting rows.

Column 1Column 2Column 3Column 4Column 5
  • Javascript
  • HTML
  • CSS
  • Ajax
  • Server-side script

The Javascript shown below is used to initialise the table shown in this example:

In addition to the above code, the following Javascript library files are loaded for use in this example:

The HTML shown below is the raw HTML table element, before it has been enhanced by DataTables:

This example uses a little bit of additional CSS beyond what is loaded from the library files (below), in order to correctly display the table. The additional CSS used is shown below:

The following CSS library files are loaded for use in this example to provide the styling of the table:

This table loads data by Ajax. The latest data that has been loaded is shown below. This data will update automatically as any additional data is loaded.

Other examples

Sours: https://datatables.net/examples/api/add_row.html
PHP AJAX Add Serial Number Column To Datatables

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datatable+columns+add


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