aAbeEBtBfABrAXW~~| G766566884ZZ-~B~ 6965VCCB~ G7655686VCBC 6666846684665G76666996-~C-~CBWP9ZCZZZZZZ-

DataTable.` A crystal has many sides. In a similar sense, computer data has many rows and columns. The DataTable class stores rows and columns of data.`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.`First program.` Data can come from a database, from a method, from memory. Here, GetTable generates a table with 4 columns of different types. `Then: `The table could be persisted to disk, displayed, or stored in memory. It is like any other object.`GetTable: `This method creates a new DataTable reference. It adds 4 column collections, then 5 rows.`Typeof: `We must specify a type (as with typeof) to create a Column. All fields from rows in this column must have this type.`Foreach-loop.` 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. `Foreach `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. `Compare Rows `datatable-compare-rows`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.`Field `datarow-field`Rows: `Often we must access the rows of a DataTable. The Rows property, which can be looped over, is ideal here.`Using.` DataTable can be placed in a using statement. This can help programs' performance. Often the using block construct helps improve resource management. `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 `using`Dispose: `When Dispose is called, native resources are released. This may help resource usage problems.`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. `DataTable works well with DataGridView. It makes DataGridView simpler and easier.`DataGridView `datagridview`Caution: `DataGridView has performance problems with manually adding rows. Using DataTable, List and DataSource helps.`Notes on example.` The code creates a DataTable and populates it with data. It is an entire Form and can be dropped into a Windows Forms application with a DataGridView in the designer. `Arrays: `The two arrays are initialized in the class and constructor. They contain column information.`Sorry for the confusing code. The important parts are how we interact with the DataTable, as with Columns.Add.`Loop through columns.` We have a collection that contains many arrays. Each of those arrays needs to be a new column. We use DataTable's methods to expand its size. `Add: `We add the column names to our DataTable with Columns.Add. These are the column headers.`DataTable requires objects to assign to the cells. Objects can hold any type of data.`Object `object`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. `Sometimes: `It is helpful to assign DataSource to null to clear it—this internally resets the data binding.`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 `convert-list-datatable`Many DataTable-List conversions may be needed. Often conversions require custom logic to be successful.`Rows.` Two important parts of DataTable are its Rows and Columns collections. With Rows, we access fields from a DataTable. We can loop over Rows with foreach. `DataRow `datarow`Columns.` Think of columns as templates for rows. The fields in rows must adhere to the types specified in the corresponding DataColumns. Only a few columns are usually needed. `DataColumn `datacolumn`DataSet.` We can combine multiple DataTable instances into one collection with the DataSet type. So a DataSet is a set of DataTables (and other things from System.Data). `DataSet `dataset`DataView.` With this type, we can sort a DataTable's representation. We use the Sort property. The underlying data is not mutated. `DataView `dataview`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. `Select `datatable-select`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. `RowChanged `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.

XYZ203:DQDQbJA%{ky9{7{Fg{7?{_yqvzvPvPv.{v.v.v.v.v.KDQDQbJA%{gy9W@p9ahz'zDQDQbJA%{_Vyq{vPv.9v.v.9='P DQDQbBJ{7{:{7oPyqoP{7{:U{7oSyqobB{Fv{ESvq{Fv{ESvq{y{7{g{7B{_yq{WwiyS]{Py{jv{Ejnoyqo{Epo@EpSE{R]]{jpwiy]yKF9qyy YY; YY.DataYYY { XYX{Z XXYYthe DataTable. XXZDataTableZ tableYGetTable();Z XXYUse the DataTable here with SQL. XZ}Z X/Y<Y> X/YThis eY mY generates a DataTable. X/Y</Y> XZYDataTable ZGetTableZ() X{Z XXYHere we cY a DataTable with four columns. XXZDataTable tableYYDataTable(); XXtable.Columns.Y"Dosage", typeof(Y)); XXtable.Columns.Y"Drug", typeof(Y)); XXtable.Columns.Y"Patient", typeof(Y)); XXtable.Columns.Y"Date", typeof(Y));Z XXYHere we add five DataRows. XXZtable.Rows.YZ25Z, "Indocin", "David", Y.Now); XXtable.Rows.YZ50Z, "Enebrel", "Sam", Y.Now); XXtable.Rows.YZ10Z, "Hydralazine", "Christoff", Y.Now); XXtable.Rows.YZ21Z, "Combivent", "Janet", Y.Now); XXtable.Rows.YZ100Z, "Dilantin", "Melanie", Y.Now); XXY table; X} }Z YY; YY.DataYYY { XYX{Z XXYThis uses the GetTable mY (please paste it in). XXZDataTable dataYGetTable();Z XXYYover all rows. XXZY (DataRow rowYdata.ZRowsZ) XX{Z XXXYY Y of first field as Yeger. XXXZYrow.ZField<Y>Z(0)); XX} X} } Z 25 50 10 21 100Z YY; YY.DataYYY { XYX{Z XXYSafely cYYdispose of a DataTable. XXZusingZ (DataTable tableYYDataTable()) XX{Z XXXYTwo columns. XXXZtable.Columns.YZ"Name"Z, typeof(Y)); XXXtable.Columns.YZ"Date"Z, typeof(Y));Z XXXYAdd two rows. XXXZtable.Rows.YZ"cat"Z, Y.Now); XXXtable.Rows.YZ"dog"Z, Y.Today);Z XXXYY first field. XXXZYtable.Rows[0].Field<Y>(0)); XX} X} } Z catZ YYY.Data; YY.Windows.FormsYnamespace WindowsFormsApplication1 { XYpartial YForm1 : Form X{Z XX/Y<Y> XX/YCY column names. XX/Y</Y> XXZY<Y> _namesYYY<Y>();Z XX/Y<Y> XX/YCY column data Ys. XX/Y</Y> XXZY<double[]> _dataYYYY<double[]>()YXXYForm1() XX{ XXXInitializeComponent();Z XXXYEY column. XXXZ_names.Y"Cat");Z XXXYThree Ys of cat data. XXXZ_dataY.YYdouble[] XXX{ XXXXZ1.0Z, XXXXZ2.2Z, XXXXZ3.4Z XXX});Z XXXYAnother eY column. XXXZ_names.Y"Dog");Z XXXYAdd three Ys of dog data. XXXZ_dataY.YYdouble[] XXX{ XXXXZ3.3Z, XXXXZ5.0Z, XXXXZ7.0Z XXX});Z XXXYRender the DataGridView. XXXZdataGridView1.DataSourceYGetResultsTable(); XX}Z XX/Y<Y> XX/YThis mY builds a DataTable of the data. XX/Y</Y> XXZYDataTable ZGetResultsTableZ() XX{Z XXXYCY the output table. XXXZDataTableZ dYYDataTable();Z XXXYYthrough all process names. XXXZY(YiY0; i < this._dataY.Y; i++) XXX{Z XXXXYThe current process name. XXXXZY nameYthis._names[i];Z XXXXYAdd the program nameYour columns. XXXXZd.Columns.Yname);Z XXXXYAdd all of the memory YsYan object Y. XXXXZY<object> objectNumbersYYY<object>();Z XXXXYPut every column's YsYthis Y. XXXXZY (double YYthis._dataY[i]) XXXX{ XXXXXobjectNumbers.ZAddZ((object)Y); XXXX}Z XXXXYKeep adding rows until we have enough. XXXXZY (d.Rows.Y < objectNumbers.Y) XXXX{ XXXXXd.Rows.ZAddZ(); XXXX}Z XXXXYAdd each itemYthe cellsYthe column. XXXXZY(YaY0; a < objectNumbers.Y; a++) XXXX{ XXXXXd.Rows[a][i]YobjectNumbers[a]; XXXX} XXX} XXXY d; XX} X} }ZEY code that sets DataSource: C#Z ZYDraw Ycells on DataGridView. ZdataGridView1.ZDataSourceZYnull; dataGridView1.DataSourceYGetResultsTable();Z

$Y[_\DataTableRows, Fieldusing statementDataGridView