VB.Net/Database ADO.net/Table Column — различия между версиями

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Текущая версия на 12:44, 26 мая 2010

Get Colunm Data type

Imports System
Imports System.Data
Imports System.Data.SqlClient

public class MainClass
   Shared Sub Main()
      Dim thisConnection As New SqlConnection("server=(local)\SQLEXPRESS;" & _
          "integrated security=sspi;database=MyDatabase")
      "Sql Query 1
      Dim sql As String ="SELECT ID,  FirstName, LastName FROM Employee;  "
      "Create Command object
      Dim thisCommand As New SqlCommand _
         (sql, thisConnection)
      Try
         " Open Connection
         thisConnection.Open()
         Console.WriteLine("Connection Opened")
         " Execute Query
         Dim thisReader As SqlDataReader = thisCommand.ExecuteReader()
         " Get column data types
         Console.WriteLine("Data types: {0} | {1}", _
            thisReader.GetDataTypeName(0).PadLeft(13), _
            thisReader.GetDataTypeName(1))

         "Close DataReader
         thisReader.Close()
      Catch ex As SqlException
         " Display error
         Console.WriteLine("Error: " & ex.ToString())
      Finally
         " Close Connection
         thisConnection.Close()
         Console.WriteLine("Connection Closed")
      End Try
   End Sub
End Class


Get table column Name

Imports System
Imports System.Collections
Imports System.Data
Imports System.IO
Imports System.Xml.Serialization
Imports System.Windows.Forms
Imports System.Data.SqlClient

Public Class MainClass
    Shared Dim WithEvents con As SqlConnection
    Shared Sub Main()
        con = New SqlConnection("Server=(local)\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=SSPI") 
        Dim str As String = "SELECT ID, FirstName, LastName FROM Employee"
        Dim cmd As New SqlCommand(str, con)
        Dim da As New SqlDataAdapter(cmd)
        Dim ds As New DataSet()
        da.Fill(ds, "Employee")
        " Display the column names
        Dim dc As DataColumn
        For Each dc In ds.Tables(0).Columns
            Console.Write("{0,15}", dc.ColumnName)
        Next
        " Add a newline after the column headings
        Console.Write(vbCrLf)
        " Display the data for each row. Loop through the rows first.
        Dim dr As DataRow
        For Each dr In ds.Tables(0).Rows
            " Then loop through the columns for the current row.
            Dim i As Integer
            For i = 1 To ds.Tables(0).Columns.Count
                Console.Write("{0,15}", dr(i - 1))
            Next i
            " Add a line break after every row
            Console.Write(vbCrLf)
        Next
    End Sub
End Class


Read Table data by Table Column Name

Imports System
Imports System.Data
Imports System.Data.OleDb
Imports System.Data.SqlClient
Imports System.Collections
Imports System.Windows.Forms
Imports System.Resources
Public Class MainClass
    Shared Sub Main()
        "Declare variables and objects
        Dim strConnectionString As String = _
            "Provider=Microsoft.Jet.OLEDB.4.0;" & _
            "Data Source=Employee.mdb;"
        Dim objConnection As New OleDbConnection(strConnectionString)
        Dim strSQL As String = _
           "SELECT FirstName, LastName FROM Employee"
        Dim objCommand As New OleDbCommand(strSQL, objConnection)
        Dim objDataAdapter As New OleDbDataAdapter(objCommand)
        Dim objDataTable As New Data.DataTable("Employee")
        Dim objDataRow As DataRow
        Try
            "Open the database connection
            objConnection.Open()
            "Fill the DataTable object
            objDataAdapter.Fill(objDataTable)
            "Load the list box on the form
            For Each objDataRow In objDataTable.Rows
                Console.WriteLine(objDataRow.Item("FirstName") & " " & _
                    objDataRow.Item("LastName"))
            Next
        Catch OleDbExceptionErr As OleDbException
            "Write the exception
            Console.WriteLine(OleDbExceptionErr.Message)
        Catch InvalidOperationExceptionErr As InvalidOperationException
            "Write the exception
            Console.WriteLine(InvalidOperationExceptionErr.Message)
        End Try
        "Close the database connection
        objConnection.Close()
        "Clean up
        objDataRow = Nothing
        objDataTable.Dispose()
        objDataTable = Nothing
        objDataAdapter.Dispose()
        objDataAdapter = Nothing
        objCommand.Dispose()
        objCommand = Nothing
        objConnection.Dispose()
        objConnection = Nothing
    End Sub
End Class

<A href="http://www.vbex.ru/Code/VBDownload/Employee.zip">Employee.zip( 7 k)</a>