Löschen Sie alle Zugriff Datenbanktabellendaten

Question

Ich habe eine Access-Datenbank, die ich mit C# manipuliere.

Ich habe es verbunden, abgerufen einen Datensatz und kann Zeilen zu einer Tabelle hinzufügen. Jetzt versuche ich einen Tisch zu säubern und ich kann ihn nicht zur Arbeit bringen.

Ich habe TRUNCATE TABLE table_name versucht, aber das löst eine Ausnahme aus, dass ich entweder DELETE, INSERT, PROCEDURE, SELECT or UPDATE verwenden müssen, und ich habe Delete FROM table_name jedoch versucht, die eine DBConcurrenceyException wirft. Hier

ist, was ich zu versucht, den Tisch zu abzuräumen:

private void ClearBut_Click(object sender, EventArgs e) 
{ 
    OleDbDataAdapter dtaAdpTestTableClear = new OleDbDataAdapter(); 
    OleDbCommand command; 

    command = new OleDbCommand("DELETE FROM TestTable", con); 

    dtaAdpTestTableClear.DeleteCommand = command; 

    foreach (DataRow row in dsWCSDHDB.Tables["TestTable"].Rows) 
    { 
     row.Delete(); 
    } 

    dtaAdpTestTableClear.Update(dsWCSDHDB.Tables["TestTable"]); 
} 

Meine andere Methode add

private void Add_Click(object sender, EventArgs e) 
{ 
    OleDbDataAdapter dtaAdpTestTableInsertNewRow = new OleDbDataAdapter(); 
    OleDbCommand command; 

    // Create the InsertCommand. 
    // This is needed as DataAdaptor.InsertCommand() is called during the update to insert the row into the database. It requires an insert query 
    command = new OleDbCommand("INSERT INTO TestTable (id, someData) " +"VALUES (?, ?)", con); //We create a dbcommand the command is, Querytype, what we are doing with it, what table, (columns we are using), concat, Values we will be adding(as ? for now as we will pass this data in latter), connection to the database 

    command.Parameters.Add("id", OleDbType.Char, 5, "id"); //this is where we add a parameter to the command function. we add one per column in the row (columns we are using name, value type, column length, source column, these parameters will replace the ? in the query above 
    command.Parameters.Add("someData", OleDbType.VarChar, 40, "someData"); 

    dtaAdpTestTableInsertNewRow.InsertCommand = command;// we attach this command to the Insert command function of the adapter that we are using 

    //Create the new row 
    DataRow row = dsWCSDHDB.Tables["TestTable"].NewRow(); //Create a new empty row that is formated for the TestTable table 
    row["someData"] = AddValueTextBox.Text.ToString();// add in the values 

    //Add the new row to the dataset table 
    dsWCSDHDB.Tables["TestTable"].Rows.Add(row); //adds this new row to the clients dataset 

    //Updates the database table with the values of the clients dataset Table 
    //For this to work you need to build a proper data adapter that is using a query taylered for the table you are using. 
    //Unfortunately although it would be nice to be able to add and use tables to the database with out changing the code you cant build a generic one that works for all tables in the database. 
    //this is because different tables can have different fields and column lengths . 
    //there is a example of how to build one below 

    //Update the database table with the values of the clients dataset Table 
    dtaAdpTestTableInsertNewRow.Update(dsWCSDHDB.Tables["TestTable"]); // using the adapter that we created above we update the database with the clients dataset. 
} 

Answer 1

Sie müssen nur ExecuteNonQuery

private void ClearBut_Click(object sender, EventArgs e) 
{ 
    string comand = "DELETE FROM TestTable" 
    OleDbCommand cmd = new OleDbCommand(comand, con); 
    cmd.ExecuteNonQuery(); 

}