Csharp/C Sharp/Database ADO.net/DataTable

Filter sort based on DataTableCollection

using System;
using System.Data;
using System.Data.SqlClient;
   class FilterSort
   {
      static void Main(string[] args)
      {
         string connString = "server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI";
         string sql1 = @"select * from employee;";
         string sql2 = @"select firstname, lastname from employee";
         string sql = sql1 + sql2;
         SqlConnection conn = new SqlConnection(connString);
         try {
            SqlDataAdapter da = new SqlDataAdapter();
            da.SelectCommand = new SqlCommand(sql, conn);
            DataSet ds = new DataSet();
            da.Fill(ds, "employee");
            DataTableCollection dtc = ds.Tables;
            Console.WriteLine("Results from Customers table:");
            Console.WriteLine("FirstName".PadRight(20) + "LastName".PadLeft(23) + "\n");
            string fl = "FirstName = "Z"";
            string srt = "LastName asc";
            foreach (DataRow row in dtc["Employee"].Select(fl, srt))
            {
               Console.WriteLine(
                  "{0}\t{1}", 
                  row["FirstName"].ToString().PadRight(25),
                  row["LastName"]);
            }
            Console.WriteLine("Results from Products table:");
            Console.WriteLine("FirstName".PadRight(20) + "LastName".PadLeft(21) + "\n");
            foreach (DataRow row in dtc[1].Rows){
               Console.WriteLine("{0}\t{1}", row["FirstName"].ToString().PadRight(25),
                  row["LastName"]);
            }
         } catch(Exception e) {
            Console.WriteLine("Error: " + e);
         } finally {
            conn.Close();
         }
      }
   }

illustrates how to specify and use a relationship between two DataTable objects

/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
  Example23_6.cs illustrates how to specify and use a
  relationship between two DataTable objects
*/
using System;
using System.Data;
using System.Data.SqlClient;
public class Example23_6
{
  public static void Main()
  {
    // formulate a string containing the details of the
    // database connection
    string connectionString =
      "server=localhost;database=Northwind;uid=sa;pwd=sa";
    // create a SqlConnection object to connect to the
    // database, passing the connection string to the constructor
    SqlConnection mySqlConnection =
      new SqlConnection(connectionString);
    // formulate a string containing a SELECT statement to
    // retrieve a row from the Customers table
    string selectString =
      "SELECT CustomerID, CompanyName " +
      "FROM Customers " +
      "WHERE CustomerID = "ALFKI"";
    // create a SqlCommand object to hold the SELECT statement
    SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
    // set the CommandText property of the SqlCommand object to
    // the SELECT string
    mySqlCommand.rumandText = selectString;
    // create a SqlDataAdapter object
    SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
    // set the SelectCommand property of the SqlAdapter object
    // to the SqlCommand object
    mySqlDataAdapter.SelectCommand = mySqlCommand;
    // create a DataSet object to store the results of
    // the SELECT statement
    DataSet myDataSet = new DataSet();
    // open the database connection using the
    // Open() method of the SqlConnection object
    mySqlConnection.Open();
    // use the Fill() method of the SqlDataAdapter object to
    // retrieve the rows from the database, storing the rows
    // in a DataTable named "Customers"
    mySqlDataAdapter.Fill(myDataSet, "Customers");
    // formulate a string containing a SELECT statement to
    // retrieve the rows from the Orders table where the CustomerID
    // column is equal to ALFKI
    selectString =
      "SELECT OrderID, CustomerID " +
      "FROM Orders " +
      "WHERE CustomerID = "ALFKI"";
    // set the CommandText property of the SqlCommand object to
    // the SELECT string
    mySqlCommand.rumandText = selectString;
    // use the Fill() method of the SqlDataAdapter object to
    // retrieve the rows from the database, storing the rows
    // in a DataTable named "Orders"
    mySqlDataAdapter.Fill(myDataSet, "Orders");
    // use the Add() method through the Relations property
    // to define a relationship between the Customers and
    // Orders DataTable objects
    myDataSet.Relations.Add(
      "Orders",
      myDataSet.Tables["Customers"].Columns["CustomerID"],
      myDataSet.Tables["Orders"].Columns["CustomerID"]
    );
    // display the rows in the Customers and Orders DataTable objects,
    // using the GetChildRows() method to get the orders for the
    // customer
    DataTable customers = myDataSet.Tables["Customers"];
    foreach (DataRow customer in customers.Rows)
    {
      Console.WriteLine("CustomerID = " + customer["CustomerID"]);
      Console.WriteLine("CompanyName = " + customer["CompanyName"]);
      DataRow[] orders = customer.GetChildRows("Orders");
      Console.WriteLine("This customer placed the following orders:");
      foreach (DataRow order in orders)
      {
        Console.WriteLine("  OrderID = " + order["OrderID"]);
      }
    }
    // close the database connection using the Close() method
    // of the SqlConnection object
    mySqlConnection.Close();
  }
}

illustrates the use of adding, modifying, and deleting a row in a DataTable object and synchronizing those changes with the

/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
  Example23_3.cs illustrates the use of adding, modifying, and deleting
  a row in a DataTable object and synchronizing those changes with the
  database
*/
using System;
using System.Data;
using System.Data.SqlClient;
public class Example23_3
{
  public static void DisplayDataTable(DataTable myDataTable)
  {
    // display the columns for each row in the DataTable,
    // using a DataRow object to access each row in the DataTable
    foreach (DataRow myDataRow in myDataTable.Rows)
    {
      Console.WriteLine("CustomerID = " + myDataRow["CustomerID"]);
      Console.WriteLine("CompanyName = " + myDataRow["CompanyName"]);
      Console.WriteLine("ContactName = " + myDataRow["ContactName"]);
      Console.WriteLine("Address = " + myDataRow["Address"]);
    }
  }
  public static void AddRow(
    DataTable myDataTable
  )
  {
    Console.WriteLine("\nAdding a new row with CustomerID of "T1COM"");
    // step 1: use the NewRow() method of the DataRow object to create
    // a new row in the DataTable
    DataRow myNewDataRow = myDataTable.NewRow();
    // step 2: set the values for the columns of the new row
    myNewDataRow["CustomerID"] = "T1COM";
    myNewDataRow["CompanyName"] = "T1 Company";
    myNewDataRow["ContactName"] = "Jason Price";
    myNewDataRow["Address"] = "1 Main Street";
    // step 3: use the Add() method through the Rows property to add
    // the new DataRow to the DataTable
    myDataTable.Rows.Add(myNewDataRow);
    // step 4: use the AcceptChanges() method of the DataTable to commit
    // the changes
    myDataTable.AcceptChanges();
  }
  public static void ModifyRow(
    DataTable myDataTable
  )
  {
    Console.WriteLine("\nModifying the new row");
    // step 1: set the PrimaryKey property for the DataTable object
    DataColumn[] myPrimaryKey = new DataColumn[1];
    myPrimaryKey[0] = myDataTable.Columns["CustomerID"];
    myDataTable.PrimaryKey = myPrimaryKey;
    // step 2: use the Find() method to locate the DataRow
    // in the DataTable using the primary key value
    DataRow myEditDataRow = myDataTable.Rows.Find("T1COM");
    // step 3: change the column values
    myEditDataRow["CompanyName"] = "Widgets Inc.";
    myEditDataRow["ContactName"] = "John Smith";
    myEditDataRow["Address"] = "1 Any Street";
    // step 4: use the AcceptChanges() method of the DataTable to commit
    // the changes
    myDataTable.AcceptChanges();
    Console.WriteLine("myEditDataRow.RowState = " + myEditDataRow.RowState);
  }
  public static void RemoveRow(
    DataTable myDataTable
  )
  {
    Console.WriteLine("\nRemoving the new row");
    // step 1: set the PrimaryKey property for the DataTable object
    DataColumn[] myPrimaryKey = new DataColumn[1];
    myPrimaryKey[0] = myDataTable.Columns["CustomerID"];
    myDataTable.PrimaryKey = myPrimaryKey;
    // step 2: use the Find() method to locate the DataRow
    DataRow myRemoveDataRow = myDataTable.Rows.Find("T1COM");
    // step 3: use the Delete() method to remove the DataRow
    myRemoveDataRow.Delete();
    // step 4: use the AcceptChanges() method of the DataTable to commit
    // the changes
    myDataTable.AcceptChanges();
  }
  public static void Main()
  {
    // formulate a string containing the details of the
    // database connection
    string connectionString =
      "server=localhost;database=Northwind;uid=sa;pwd=sa";
    // create a SqlConnection object to connect to the
    // database, passing the connection string to the constructor
    SqlConnection mySqlConnection =
      new SqlConnection(connectionString);
    // formulate a SELECT statement to retrieve the
    // CustomerID, CompanyName, ContactName, and Address
    // columns for the first row from the Customers table
    string selectString =
      "SELECT CustomerID, CompanyName, ContactName, Address " +
      "FROM Customers " +
      "WHERE CustomerID = "ALFKI"";
    // create a SqlCommand object to hold the SELECT statement
    SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
    // set the CommandText property of the SqlCommand object to
    // the SELECT string
    mySqlCommand.rumandText = selectString;
    // create a SqlDataAdapter object
    SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
    // set the SelectCommand property of the SqlAdapter object
    // to the SqlCommand object
    mySqlDataAdapter.SelectCommand = mySqlCommand;
    // create a DataSet object to store the results of
    // the SELECT statement
    DataSet myDataSet = new DataSet();
    // open the database connection using the
    // Open() method of the SqlConnection object
    mySqlConnection.Open();
    // use the Fill() method of the SqlDataAdapter object to
    // retrieve the rows from the table, storing the rows locally
    // in a DataTable of the DataSet object
    Console.WriteLine("Retrieving a row from the Customers table");
    mySqlDataAdapter.Fill(myDataSet, "Customers");
    // get the DataTable object from the DataSet object
    DataTable myDataTable = myDataSet.Tables["Customers"];
    // display the rows in the DataTable object
    DisplayDataTable(myDataTable);
    // add a new row
    AddRow(myDataTable);
    DisplayDataTable(myDataTable);
    // modify a row
    ModifyRow(myDataTable);
    DisplayDataTable(myDataTable);
    // remove a row
    RemoveRow(myDataTable);
    DisplayDataTable(myDataTable);
    // use the Fill() method of the SqlDataAdapter object
    // to synchronize the changes with the database
    mySqlDataAdapter.Fill(myDataSet, "Customers");
    // close the database connection using the Close() method
    // of the SqlConnection object
    mySqlConnection.Close();
  }
}

Modify DataTable: insert data to database table

using System;
using System.Data;
using System.Data.SqlClient;
   class ModifyDataTable
   {
      static void Main()
      {
         string connString = "server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI";
         string sql = @"select * from employee";
         SqlConnection conn = new SqlConnection(connString);
         try {
            SqlDataAdapter da = new SqlDataAdapter();
            da.SelectCommand = new SqlCommand(sql, conn);
            DataSet ds = new DataSet();   
            da.Fill(ds, "employee");
            DataTable dt = ds.Tables["employee"];
            dt.Columns["firstname"].AllowDBNull = true;
            dt.Rows[0]["FirstName"] = "Joe";
            DataRow newRow = dt.NewRow();
            newRow["firstname"] = "Roy";
            newRow["lastname"] = "Beatty";
            dt.Rows.Add(newRow);
            foreach (DataRow row in dt.Rows)
            {
               Console.WriteLine("{0} {1}",
                  row["firstname"].ToString().PadRight(15),
                  row["lastname"].ToString().PadLeft(25));
            }
            
         } catch(Exception e) {
            Console.WriteLine("Error: " + e);
         } finally {
            conn.Close();
         }
      }  
   }

Print DataTable

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
class Program {
    static void Main(string[] args) {
        DataSet carsInventoryDS = new DataSet("Inventory");
        carsInventoryDS.ExtendedProperties["TimeStamp"] = DateTime.Now;
        carsInventoryDS.ExtendedProperties["Company"] = "Name";
        DataColumn carIDColumn = new DataColumn("CarID", typeof(int));
        carIDColumn.ReadOnly = true;
        carIDColumn.Caption = "Car ID";
        carIDColumn.AllowDBNull = false;
        carIDColumn.Unique = true;
        carIDColumn.AutoIncrement = true;
        carIDColumn.AutoIncrementSeed = 0;
        carIDColumn.AutoIncrementStep = 1;
        carIDColumn.ColumnMapping = MappingType.Attribute;
        DataColumn carMakeColumn = new DataColumn("Make", typeof(string));
        DataColumn carColorColumn = new DataColumn("Color", typeof(string));
        DataColumn carPetNameColumn = new DataColumn("PetName", typeof(string));
        carPetNameColumn.Caption = "Name";
        DataTable inventoryTable = new DataTable("Inventory");
        inventoryTable.Columns.AddRange(new DataColumn[] { carIDColumn, carMakeColumn, carColorColumn, carPetNameColumn });
        inventoryTable.PrimaryKey = new DataColumn[] { inventoryTable.Columns[0] };
        DataRow carRow = inventoryTable.NewRow();
        carRow["Make"] = "B";
        carRow["Color"] = "C";
        carRow["PetName"] = "A";
        inventoryTable.Rows.Add(carRow);
        carRow = inventoryTable.NewRow();
        carRow["Make"] = "S";
        carRow["Color"] = "R";
        carRow["PetName"] = "E";
        inventoryTable.Rows.Add(carRow);
        carsInventoryDS.Tables.Add(inventoryTable);
        PrintTable(carsInventoryDS.Tables["Inventory"]);
    }
    private static void PrintTable(DataTable dt) {
        DataTableReader dtReader = dt.CreateDataReader();
        while (dtReader.Read()) {
            for (int i = 0; i < dtReader.FieldCount; i++) {
                Console.Write("{0} = {1} ",
                    dtReader.GetName(i).Trim(),
                    dtReader.GetValue(i).ToString().Trim());
            }
            Console.WriteLine();
        }
        dtReader.Close();
    }
}