我是SQL Server / C＃的新手。
我的老师认为我应该使用C＃使用SqlConnection和SqlCommand将数据写入数据库。
我有一位朋友希望我帮助她完成项目，但我不知道如何从数据库中获取数据或如何从数据库中显示表格。
希望有人觉得这个问题很有用，尤其是初学者。 ：）
另外，如何连续获取特定元素？
答案 0 :(得分：1)
使用相同的sqlConnection和SqlCommand和SqlReader对象（Classes）通过Select查询从数据库中获取数据，如果需要，可以在数据网格上显示它们。只需搜索SO或谷歌。 MSDN也有很好的例子。
答案 1 :(得分：1)
如果您使用的是Windows表单，那么也许您可以使用DataGridView控件 - 请参阅这个非常简单的教程来帮助您入门：http://www.dotnetperls.com/datagridview-tutorial
对于Web应用程序，您可以使用GridView控件 - 有关各种示例，请参阅MSDN：http://msdn.microsoft.com/en-us/library/aa479339.aspx
答案 2 :(得分：0)
使用此功能（使用System.Data.SqlClient搜索和替换System.Data.OleDB）：
public override System.Data.DataTable GetDataTable(string strSQL)
{
System.Data.DataTable dt = new System.Data.DataTable();
using (System.Data.IDbConnection idb = GetConnection())
{
lock (idb)
{
try
{
using (System.Data.OleDb.OleDbDataAdapter daQueryTable = new System.Data.OleDb.OleDbDataAdapter(strSQL, (System.Data.OleDb.OleDbConnection) idb))
{
daQueryTable.Fill(dt);
} // End Using daQueryTable
} // End Try
catch (Exception ex)
{
Log("cOleDB.GetDataTable(string strSQL)", ex, strSQL);
} // End Catch
finally
{
if (idb.State != System.Data.ConnectionState.Closed)
idb.Close();
} // End Finally
} // End Lock idb
} // End Using idb
return dt;
} // End Function GetDataTable
public System.Data.IDbConnection GetConnection()
{
System.Data.OleDb.OleDbConnection oledbc= new System.Data.OleDb.OleDbConnection(m_ConnectionString.ConnectionString);
return oledbc;
}
对于有效的连接字符串，请转到： http://www.connectionstrings.com/
这是一个VBish版本：
Namespace SQL
Public Class MS_SQL
Public Const strDefaultCatalog As String = "AdventureWorks"
Public Shared Function GetConnectionString(Optional ByRef strIntitialCatalog As String = strDefaultCatalog) As String
Return strConnectionString
End Function ' GetConnectionString
Public Shared Function GetConnection(ByVal strConnectionString As String)
'GetConnectionString(strDataBaseName)
Return New System.Data.SqlClient.SqlConnection(strConnectionString)
End Function
Public Shared Function GetConnection() As System.Data.IDbConnection
Static strConnectionString As String = GetConnectionString()
Return New System.Data.SqlClient.SqlConnection(strConnectionString)
End Function ' GetConnection
Public Shared Function TestConnection() As Boolean
Dim bExceptionOccured As Boolean = False
Using dbConnection As System.Data.IDbConnection = GetConnection()
SyncLock dbConnection
Try
'Console.WriteLine("Connection timout: " + dbConnection.ConnectionTimeout.ToString)
If Not dbConnection.State = ConnectionState.Open Then
dbConnection.Open()
End If
Catch ex As Exception
bExceptionOccured = True
'Log.File.WriteText("Error opening the database connection. Check your connection string and password as well as networking and permissions.")
Log.File.WriteText("Fehler beim Öffnen der Datenbankverbindung. Bitte überprüfen Sie den Verbindungsstring und das Passwort, sowie das Netzwerk und Berechtigungen.")
'Log.File.WriteText("Exception message:")
Log.File.WriteText("Fehlerbeschreibung:")
Console.WriteLine(ex.Message)
ErrorHandling.Exception.iExitCode = ErrorHandling.Exception.ExitCode.EXIT_DATABASE_NOCONNECT
'MsgBox("Connection couldn't be opened.", MsgBoxStyle.Critical)
ErrorHandling.Exception.TerminateWithErrorcode(ErrorHandling.Exception.ExitCode.EXIT_DATABASE_NOCONNECT)
Finally
If Not dbConnection.State = ConnectionState.Closed Then
dbConnection.Close()
End If
End Try
End SyncLock ' dbConnection
End Using ' dbConnection
Return bExceptionOccured
End Function ' TestConnection
Public Shared Function GetEmbeddedSQLscript(ByVal strSearchedFileName As String) As String
Dim ass As System.Reflection.Assembly = System.Reflection.Assembly.GetAssembly(GetType(MS_SQL))
If String.IsNullOrEmpty(strSearchedFileName) Then
Throw New ArgumentNullException("strSearchedFileName")
End If
Dim strFoundRessourceName As String = Nothing
For Each strEmbeddedRessourceName As String In ass.GetManifestResourceNames()
If Not String.IsNullOrEmpty(strEmbeddedRessourceName) Then
If strEmbeddedRessourceName.EndsWith(strSearchedFileName, System.StringComparison.OrdinalIgnoreCase) Then
strFoundRessourceName = strEmbeddedRessourceName
Exit For
End If
' Console.WriteLine(strEmbeddedRessourceName)
End If
Next
If String.IsNullOrEmpty(strFoundRessourceName) Then
Throw New Exception("The script """ + strSearchedFileName + """ is not present in the embedded ressources section.")
Else
'Console.WriteLine(strFoundRessourceName)
End If
Dim strSQLscript As String = Nothing
Try
Using strmRessource As System.IO.Stream = ass.GetManifestResourceStream(strFoundRessourceName)
Using srRessourceReader As New System.IO.StreamReader(strmRessource)
strSQLscript = srRessourceReader.ReadToEnd()
srRessourceReader.Close()
End Using
strmRessource.Close()
End Using
Catch ex As Exception
Throw
End Try
Return strSQLscript
End Function ' GetEmbeddedSQLscript
Public Class cParameterStore
Public Class cParameter
Public SqlDbType As System.Data.SqlDbType = Nothing
Protected m_Value As Object = Nothing
Public Sub New(ByVal dbt As System.Data.SqlDbType, ByVal objValue As Object)
Me.SqlDbType = dbt
Me.Value = objValue
End Sub ' Constructor
Public Property Value() As Object
Get
Return Me.m_Value
End Get
Set(ByVal objValue As Object)
If objValue IsNot Nothing Then
Me.m_Value = objValue
Else
Me.m_Value = System.DBNull.Value
End If
End Set
End Property ' Value
End Class ' cParameter
Public m_dictParameters As Dictionary(Of String, cParameter) = Nothing
Sub New()
Me.m_dictParameters = New Dictionary(Of String, cParameter)
End Sub ' Constructor
Public ReadOnly Property Parameters() As Dictionary(Of String, cParameter)
Get
Return Me.m_dictParameters
End Get
End Property ' Parameters
Public Sub Add(ByVal strKey As String, ByVal dbt As System.Data.SqlDbType, ByVal objValue As Object)
If String.IsNullOrEmpty(strKey) Then
Throw New ArgumentNullException("strKey")
End If
If dbt = Nothing Then
Throw New ArgumentNullException("dbt")
End If
If Not strKey.StartsWith("@") Then
strKey = "@" + strKey
End If
m_dictParameters.Add(strKey, New cParameter(dbt, objValue))
End Sub ' Add
End Class ' cParameterStore
Public Shared Function GetNewParamterStore() As cParameterStore
Return New cParameterStore()
End Function ' GetNewParamterStore
Public Shared Sub ExecuteSQLreader(ByRef strSQL As String, ByRef strWhich As String, ByRef alSQLqueryReturnList As ArrayList)
'Dim alSQLqueryReturnList As ArrayList
'alSQLqueryReturnList = New ArrayList
Using dbConn As System.Data.IDbConnection = GetConnection()
SyncLock dbConn
Using sqlCMD As System.Data.IDbCommand = dbConn.CreateCommand()
Try
sqlCMD.CommandText = strSQL
If Not dbConn.State = System.Data.ConnectionState.Open Then
dbConn.Open()
End If
Using sdrSQLReader As System.Data.IDataReader = sqlCMD.ExecuteReader(System.Data.CommandBehavior.CloseConnection)
While sdrSQLReader.Read()
alSQLqueryReturnList.Add(sdrSQLReader.Item(strWhich).ToString())
End While
End Using
Catch QueryError As Exception
'Log.File.WriteText(String.Format("Exception in ExecuteSQLreader: {0}{1}{2}", QueryError.Message, vbCrLf, strSQL))
Log.File.WriteText(String.Format("Fehler in ExecuteSQLreader: {0}{1}{2}", QueryError.Message, vbCrLf, strSQL))
Finally
If Not dbConn.State = System.Data.ConnectionState.Closed Then
dbConn.Close()
End If
End Try
End Using ' sqlCMD
End SyncLock ' dbConn
End Using ' dbConn
End Sub ' ExecuteSQLreader
Public Shared Function ExecuteSQLstmtScalarWithParameter(ByRef strSQL As String, ByVal ParameterStore As cParameterStore) As String
Dim strReturnValue As String = ""
Using sqldbConnection As System.Data.IDbConnection = GetConnection()
SyncLock sqldbConnection
Using sqlCMD As System.Data.SqlClient.SqlCommand = sqldbConnection.CreateCommand()
sqlCMD.CommandText = strSQL
Try
'sqlCMD.Parameters.Add("@mandant", System.Data.SqlDbType.Int).Value = 5
For Each kvpThisParameter As KeyValuePair(Of String, cParameterStore.cParameter) In ParameterStore.Parameters
sqlCMD.Parameters.Add(kvpThisParameter.Key, kvpThisParameter.Value.SqlDbType).Value = kvpThisParameter.Value.Value
Next
' Open the connection
If Not sqldbConnection.State = ConnectionState.Open Then
sqldbConnection.Open()
End If
Dim objResult As Object = sqlCMD.ExecuteScalar()
If objResult IsNot Nothing Then
strReturnValue = objResult.ToString()
Else
strReturnValue = Nothing
End If
objResult = Nothing
Catch ex As System.Data.SqlClient.SqlException
'Log.File.WriteText(String.Format("Exception executing ExecuteSQLstmtScalarWithParameter: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Log.File.WriteText(String.Format("Fehler beim Ausführen von ExecuteSQLstmtScalarWithParameter: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
' No Error notification when silent
Finally
' Open the connection
If Not sqldbConnection.State = ConnectionState.Closed Then
sqldbConnection.Close()
End If
sqlCMD.Dispose()
sqldbConnection.Dispose()
End Try
End Using ' sqlCMD
End SyncLock ' sqldbConnection
End Using ' sqldbConnection
Return strReturnValue
End Function ' ExecuteSQLstmtScalarWithParameter
Public Shared Function ExecuteSQLstmtScalar(ByRef strSQL As String) As String
Dim strReturnValue As String = ""
Using sqldbConnection As System.Data.IDbConnection = GetConnection()
SyncLock sqldbConnection
Using sqlCMD As SqlClient.SqlCommand = sqldbConnection.CreateCommand()
sqlCMD.CommandText = strSQL
Try
' Open the connection
If Not sqldbConnection.State = ConnectionState.Open Then
sqldbConnection.Open()
End If
Dim objResult As Object = sqlCMD.ExecuteScalar()
If objResult IsNot Nothing Then
strReturnValue = objResult.ToString()
Else
strReturnValue = Nothing
End If
objResult = Nothing
Catch ex As System.Data.SqlClient.SqlException
'Log.File.WriteText(String.Format("Exception executing ExecuteSQLstmtScalar: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Log.File.WriteText(String.Format("Fehler beim Ausführen von ExecuteSQLstmtScalar: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
' No Error notification when silent
Finally
' Open the connection
If Not sqldbConnection.State = ConnectionState.Closed Then
sqldbConnection.Close()
End If
sqlCMD.Dispose()
sqldbConnection.Dispose()
End Try
End Using ' sqlCMD
End SyncLock ' sqldbConnection
End Using ' sqldbConnection
Return strReturnValue
End Function ' ExecuteSQLstmtScalar
Public Shared Sub ExecuteSQLStmtWithParameters(ByRef strSQL As String, ByVal ParameterStore As cParameterStore)
Using conn As System.Data.IDbConnection = GetConnection()
SyncLock conn
Using sqlCMD As System.Data.SqlClient.SqlCommand = conn.CreateCommand
sqlCMD.CommandText = strSQL
'sqlCMD.Parameters.Add("@mandant", System.Data.SqlDbType.Int).Value = 5
For Each kvpThisParameter As KeyValuePair(Of String, cParameterStore.cParameter) In ParameterStore.Parameters
sqlCMD.Parameters.Add(kvpThisParameter.Key, kvpThisParameter.Value.SqlDbType).Value = kvpThisParameter.Value.Value
Next
'Dim x As System.Data.IDataParameter = cmd.CreateParameter()
'x.ParameterName = ""
'x.Value = ""
'sqlCMD.Parameters.Add(x)
Try
' Open the connection
If Not conn.State = ConnectionState.Open Then
conn.Open()
End If
sqlCMD.ExecuteNonQuery()
'Log.File.WriteText(String.Format("Command ExecuteSQLStmtWithParameters completed successfully. {0}", vbCrLf + "strSQL=" + strSQL))
Catch ex As SqlClient.SqlException
'Log.File.WriteText(String.Format("Exception executing ExecuteSQLStmtWithParameters: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Log.File.WriteText(String.Format("Fehler beim Ausführen von ExecuteSQLStmtWithParameters: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Finally
If Not conn.State = ConnectionState.Closed Then
conn.Close()
End If
End Try
End Using ' sqlCMD
End SyncLock ' conn
End Using ' conn
End Sub ' ExecuteSQLStmtWithParameters
Public Shared Sub ExecuteSQLStmtNoNotification(ByRef strSQL As String, Optional ByRef strConnectionString As String = Nothing)
Using conn As System.Data.IDbConnection = GetConnection()
SyncLock conn
Using cmd As System.Data.IDbCommand = conn.CreateCommand()
cmd.CommandText = strSQL
Try
' Open the connection
If Not conn.State = ConnectionState.Open Then
conn.Open()
End If
cmd.ExecuteNonQuery()
'Log.File.WriteText(String.Format("Command ExecuteSQLStmtNoNotification completed successfully. {0}", vbCrLf + "strSQL=" + strSQL))
Catch ex As SqlClient.SqlException
'Log.File.WriteText(String.Format("Exception executing ExecuteSQLStmtNoNotification: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Log.File.WriteText(String.Format("Fehler beim Ausführen von ExecuteSQLStmtNoNotification: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Finally
If Not conn.State = ConnectionState.Closed Then
conn.Close()
End If
End Try
End Using ' cmd
End SyncLock ' conn
End Using ' conn
End Sub 'ExecuteSQLStmtNoNotification
Public Shared Function ExecuteSQLStmtNoNotificationReturnError(ByRef strSQL As String, Optional ByRef strConnectionString As String = Nothing) As System.Data.SqlClient.SqlException
Dim eErrorCatcher As System.Data.SqlClient.SqlException = Nothing
Using conn As System.Data.IDbConnection = GetConnection()
SyncLock conn
Using sqlCMD As System.Data.IDbCommand = conn.CreateCommand()
Try
sqlCMD.CommandText = strSQL
' Open the connection
If Not conn.State = System.Data.ConnectionState.Open Then
conn.Open()
End If
sqlCMD.ExecuteNonQuery()
Catch ex As System.Data.SqlClient.SqlException
eErrorCatcher = ex
Log.File.WriteText(String.Format("Fehler beim Ausführen von ExecuteSQLStmtNoNotificationReturnError: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Catch ex As Exception
Log.File.WriteText(String.Format("Unerwarteter Fehler beim Ausführen von ExecuteSQLStmtNoNotificationReturnError: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Finally
If Not conn.State = System.Data.ConnectionState.Closed Then
conn.Close()
End If
End Try
End Using ' sqlCMD
End SyncLock ' conn
End Using ' conn
Return eErrorCatcher
End Function 'ExecuteSQLStmtNoNotificationReturnError
Public Shared Sub ExecuteSQLStmtSilent(ByRef strSQL As String)
Using conn As System.Data.IDbConnection = GetConnection()
SyncLock conn
Using cmd As System.Data.IDbCommand = conn.CreateCommand()
cmd.CommandText = strSQL
Try
' Open the connection
If Not conn.State = ConnectionState.Open Then
conn.Open()
End If
cmd.ExecuteNonQuery()
Catch ex As System.Data.SqlClient.SqlException
' No Error notification in silent mode
'Log.File.WriteText(String.Format("Exception executing ExecuteSQLStmtSilent: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Log.File.WriteText(String.Format("Fehler beim Ausführen von ExecuteSQLStmtSilent: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Finally
' Open the connection
If Not conn.State = ConnectionState.Closed Then
conn.Close()
End If
End Try
End Using ' cmd
End SyncLock ' conn
End Using ' conn
End Sub 'ExecuteSQLStmtSilent
Public Shared Sub GetDataSetWithParameters(ByRef strSQL As String, ByRef dsDataFromTable As DataSet, ByRef ParameterStore As cParameterStore)
GetDataSetWithParameters(strSQL, dsDataFromTable, "ThisTable", ParameterStore)
End Sub ' GetDataSetWithParameters
Public Shared Sub GetDataSetWithParameters(ByRef strSQL As String, ByRef dsDataFromTable As DataSet, ByVal strTableName As String, ByRef ParameterStore As cParameterStore)
Using sqlConnection As System.Data.SqlClient.SqlConnection = GetConnection()
SyncLock sqlConnection
Using sqlCMD As System.Data.SqlClient.SqlCommand = sqlConnection.CreateCommand()
sqlCMD.CommandText = strSQL
'sqlCMD.Parameters.Add("@mandant", System.Data.SqlDbType.Int).Value = 5
Try
For Each kvpThisParameter As KeyValuePair(Of String, cParameterStore.cParameter) In ParameterStore.Parameters
sqlCMD.Parameters.Add(kvpThisParameter.Key, kvpThisParameter.Value.SqlDbType).Value = kvpThisParameter.Value.Value
Next
Catch ex As Exception
Log.File.WriteText(String.Format("Fehler in GetDataSetWithParameters (at adding parameters): {0}", ex.Message + Environment.NewLine + "strSQL=" + strSQL))
End Try
Using daQueryTable As System.Data.SqlClient.SqlDataAdapter = New System.Data.SqlClient.SqlDataAdapter(sqlCMD)
Try
dsDataFromTable = New System.Data.DataSet(strTableName)
If Not sqlConnection.State = System.Data.ConnectionState.Open Then
sqlConnection.Open()
End If
daQueryTable.Fill(dsDataFromTable)
Catch ex As Exception
'Log.File.WriteText(String.Format("Exception executing GetDataSetWithParameters: {0}", ex.Message + vbCrLf + "strSQL=" + strSQL))
Log.File.WriteText(String.Format("Fehler in GetDataSetWithParameters: {0}", ex.Message + Environment.NewLine + "strSQL=" + strSQL))
Finally
If Not sqlConnection.State = System.Data.ConnectionState.Closed Then
sqlConnection.Close()
End If
End Try
End Using ' daQueryTable
End Using ' sqlCMD
End SyncLock ' sqlConnection
End Using ' sqlConnection
End Sub ' GetDataSetWithParameters
Public Shared Sub GetDataSet(ByRef strSQL As String, ByRef dsDataFromTable As DataSet)
GetDataSet(strSQL, dsDataFromTable, "ThisTable")
End Sub ' GetDataSetWithParameters
Public Shared Sub GetDataSet(ByRef strSQL As String, ByRef dsDataFromTable As DataSet, ByVal strTableName As String)
Using sqlConnection As System.Data.SqlClient.SqlConnection = GetConnection()
SyncLock sqlConnection
Using daQueryTable As System.Data.SqlClient.SqlDataAdapter = New System.Data.SqlClient.SqlDataAdapter(strSQL, sqlConnection)
Try
dsDataFromTable = New System.Data.DataSet(strTableName)
If Not sqlConnection.State = System.Data.ConnectionState.Open Then
sqlConnection.Open()
End If
daQueryTable.Fill(dsDataFromTable)
Catch ex As Exception
'Log.File.WriteText(String.Format("Exception executing GetDataSetWithParameters: {0}", ex.Message.ToString() + vbCrLf + "strSQL=" + strSQL))
Log.File.WriteText(String.Format("Fehler in GetDataSetWithParameters: {0}", ex.Message + Environment.NewLine + "strSQL=" + strSQL))
Finally
If Not sqlConnection.State = System.Data.ConnectionState.Closed Then
sqlConnection.Close()
End If
End Try
End Using ' daQueryTable
End SyncLock ' sqlConnection
End Using ' sqlConnection
End Sub ' GetDataSet
End Class
End Namespace
答案 3 :(得分：0)
很快从另一个论坛复制;这应该让你开始：
如果您不是在寻找分页和更新内置支持，只需使用转发器，代码应如下所示。
<asp:Repeater id="myRepeater" runat="server">
<ItemTemplate>
<a href='<%# Eval("client_url") %>'><%# Eval("client_name") %> </a>
</ItemTemplate>
</asp:Repeater>
在你的守则背后......
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack == false)
{
string strConnection = ConfigurationManager.ConnectionStrings["connectionString"].ConnectionString; // Add your connection string here if you have it in your web.config file, if not, just type it out manually.
string mySelectQuery = "SELECT client_url, client_name FROM Clients";
SqlConnection myConnection = new SqlConnection(strConnection);
SqlCommand myCommand = new SqlCommand(mySelectQuery, myConnection);
myConnection.Open();
SqlDataReader myReader;
myReader = myCommand.ExecuteReader();
myRepeater.DataSource = myReader;
myRepeater.DataBind();
myReader.Close();
myConnection.Close();
}
}