How to add a able object to Dataset

With help, we can find the following: Code Implementation

Example

[C #] the following example creates two able objects and a datarelation object, and adds these new objects to dataset. Call the DataGrid. setdatabinding method to display these tables in the DataGrid Control.

[C #]

// Put the next line into the declarations section.

Private system. Data. dataset mydataset;



Private void makedatatables (){

// Run all of the functions.

Makeparenttable ();

Makechildtable ();

Makedatarelation ();

Bindtodatagrid ();

}



Private void makeparenttable (){

// Create a new datatable.

System. Data. datatable mydatatable = new datatable ("parenttable ");

// Declare variables for datacolumn and datarow objects.

Datacolumn mydatacolumn;

Datarow mydatarow;



// Create new datacolumn, set datatype, columnname and add to datatable.

Mydatacolumn = new datacolumn ();

Mydatacolumn. datatype = system. type. GetType ("system. int32 ");

Mydatacolumn. columnname = "ID ";

Mydatacolumn. readonly = true;

Mydatacolumn. Unique = true;

// Add the column to the datacolumncollection.

Mydatatable. Columns. Add (mydatacolumn );



// Create second column.

Mydatacolumn = new datacolumn ();

Mydatacolumn. datatype = system. type. GetType ("system. String ");

Mydatacolumn. columnname = "parentitem ";

Mydatacolumn. autoincrement = false;

Mydatacolumn. Caption = "parentitem ";

Mydatacolumn. readonly = false;

Mydatacolumn. Unique = false;

// Add the column to the table.

Mydatatable. Columns. Add (mydatacolumn );



// Make the ID column the primary key column.

Datacolumn [] primarykeycolumns = new datacolumn [1];

Primarykeycolumns [0] = mydatatable. Columns ["ID"];

Mydatatable. primarykey = primarykeycolumns;



// Instantiate the dataset variable.

Mydataset = new dataset ();

// Add the new datatable to the dataset.

Mydataset. Tables. Add (mydatatable );



// Create three new datarow objects and add them to the datatable

For (INT I = 0; I <= 2; I ++ ){

Mydatarow = mydatatable. newrow ();

Mydatarow ["ID"] = I;

Mydatarow ["parentitem"] = "parentitem" + I;

Mydatatable. Rows. Add (mydatarow );

}

}



Private void makechildtable (){

// Create a new datatable.

Datatable mydatatable = new datatable ("childtable ");

Datacolumn mydatacolumn;

Datarow mydatarow;



// Create first column and add to the datatable.

Mydatacolumn = new datacolumn ();

Mydatacolumn. datatype = system. type. GetType ("system. int32 ");

Mydatacolumn. columnname = "childid ";

Mydatacolumn. autoincrement = true;

Mydatacolumn. Caption = "ID ";

Mydatacolumn. readonly = true;

Mydatacolumn. Unique = true;

// Add the column to the datacolumncollection.

Mydatatable. Columns. Add (mydatacolumn );



// Create second column.

Mydatacolumn = new datacolumn ();

Mydatacolumn. datatype = system. type. GetType ("system. String ");

Mydatacolumn. columnname = "childitem ";

Mydatacolumn. autoincrement = false;

Mydatacolumn. Caption = "childitem ";

Mydatacolumn. readonly = false;

Mydatacolumn. Unique = false;

Mydatatable. Columns. Add (mydatacolumn );



// Create third column.

Mydatacolumn = new datacolumn ();

Mydatacolumn. datatype = system. type. GetType ("system. int32 ");

Mydatacolumn. columnname = "parentid ";

Mydatacolumn. autoincrement = false;

Mydatacolumn. Caption = "parentid ";

Mydatacolumn. readonly = false;

Mydatacolumn. Unique = false;

Mydatatable. Columns. Add (mydatacolumn );



Mydataset. Tables. Add (mydatatable );

// Create three sets of datarow objects, five rows each, and add to datatable.

For (INT I = 0; I <= 4; I ++ ){

Mydatarow = mydatatable. newrow ();

Mydatarow ["childid"] = I;

Mydatarow ["childitem"] = "item" + I;

Mydatarow ["parentid"] = 0;

Mydatatable. Rows. Add (mydatarow );

}

For (INT I = 0; I <= 4; I ++ ){

Mydatarow = mydatatable. newrow ();

Mydatarow ["childid"] = I + 5;

Mydatarow ["childitem"] = "item" + I;

Mydatarow ["parentid"] = 1;

Mydatatable. Rows. Add (mydatarow );

}

For (INT I = 0; I <= 4; I ++ ){

Mydatarow = mydatatable. newrow ();

Mydatarow ["childid"] = I + 10;

Mydatarow ["childitem"] = "item" + I;

Mydatarow ["parentid"] = 2;

Mydatatable. Rows. Add (mydatarow );

}

}



Private void makedatarelation (){

// Datarelation requires two datacolumn (Parent and Child) and a name.

Datarelation mydatarelation;

Datacolumn parentcolumn;

Datacolumn childcolumn;

Parentcolumn = mydataset. Tables ["parenttable"]. Columns ["ID"];

Childcolumn = mydataset. Tables ["childtable"]. Columns ["parentid"];

Mydatarelation = new datarelation ("parent2child", parentcolumn, childcolumn );

Mydataset. Tables ["childtable"]. parentrelations. Add (mydatarelation );

}



Private void bindtodatagrid (){

// Instruct the DataGrid to bind to the dataset, with

// Parenttable as the topmost datatable.

Datagrid1.setdatabinding (mydataset, "parenttable ");

}

However, in the actual development process, we generally read data through the database and put it in dataset. The following shows how to connect to the data.

Private dataset myds;

Myds = new dataset ();

Sqldatabase sqldb = new sqldatabase (DSN );

String strsql = "select * from ";

System. Data. dataset DS = sqldb. createset (strsql, "");

Datatable DT;

Dt = Ds. Tables [0]. Clone ();

Myds. Tables. Add (DT );

String strsql1 = "select * from B ";

System. Data. dataset ds1 = sqldb. createset (strsql1, "B ");

Datatable dt1;

Dt1 = ds1.tables [0]. Clone ();

Myds. Tables. Add (dt1 );

Sqldb. closeconnection ();

Myds. Merge (Ds. Tables [0]);

Myds. Merge (ds1.tables [0]);

This. datagrid1.datasource = myds;



This. datagrid1.databind ();

This. datagrid2.datasource = myds. Tables [1];

This. Maid ();