C#datatable Learning Experience

C#datatable Learning Experience

I. Datasets, DataTable, DataRow, DataColumn

1 "Adding a DataTable to a dataset

DATASET.TABLES.ADD (DataTable)

Instance:

DataSet ds=new DataSet ();

DataTable table=new DataTable ("Student Table");

Ds. Tables.add (table); 2 "Reading a DataTable from a dataset

Datatable=dataset.tables[0] or dataset.tables["table name"]

Instance:

DataTable Table=ds[i] or DataTable table=ds["Student Table"]

I is the index value in the dataset, because the dataset can hold more than one DataTable, you can find a DataTable based on the index value or write the DataTable name directly to find a DataTable 3 "Add row DataTable t=new      DataTable ();      DataRow R=t.newrow ();      r["column name"]= column value; T.rows.add (R);

Instance:

DataTable: Student Table

ID Name

1 Xun

Code:

DataTable t=new DataTable ("Student Table");

DataRow R=t.newrow ();

r["id"]=2;

r["Name"]=XUN2;

T.rows.add (R);

4 "Add column

DATATABLE.COLUMNS.ADD ("Column name", Type.GetType ("Data type")); 5 "Reading column values from rows

datarow["column name"] or Datarow[datacolumn]; 6 "Reading column values from a DataTable

DataTable table;

A, table. rows[i]["column name"]

b, table. Rows[i][i]

C, table[i]. Column names (column names are not quoted)

7 "read out a specific line

DataTable table;

Datarow[] selectrow=table. Select ("Column name = '" + holds a specific variable.) ToString () + "'");

Select one of the rows: selectrow[index]

Ii. Delete rows in a DataTable three methods: (DataTable.Rows.Remove (DataRow Dr), DataTable.Rows.RemoveAt (i), Datarow.delete ())

Delete Rows in a DataTable to pay attention to index problems, there are generally two ways: 1 "with a For loop, note that the counter initial value is the table length, self-reduction loop. DataTable.Rows.RemoveAt (i) should be noted. 2 "With the Select method of the DataTable, note that the parameter of the method is string filter 3" Delete () after a DataTable is required. The Acceptechanges () method confirms a complete deletion, because delete () only flags the status of the corresponding column as deleted, and it can be passed through a DataTable. RejectChanges () rollback to make the row undelete. To delete multiple rows, you can use Delete () consecutively, and then use the Acceptechanges () method to confirm the deletion.

C#datatable Learning Experience