如何使用adox向access表添加外键

Question

我正在尝试创建一个有两个表的数据库。我想在其中一个加一个外键。但是下面的代码不起作用，我调试它，发现唯一的问题是添加外键。

private static bool creatDatabase()
    {
        bool result = false;

        Catalog cat = new Catalog();
        Table tableCustomer = new Table();
        Table tableAddresses = new Table();

        //Create the table Customer and it's fields. 
        tableCustomer.Name = "Customer";
        tableCustomer.Columns.Append("Customer_ID", ADOX.DataTypeEnum.adInteger);
        tableCustomer.Keys.Append("PrimaryKEy", KeyTypeEnum.adKeyPrimary, "Customer_ID");
        tableCustomer.Columns.Append("Name", ADOX.DataTypeEnum.adVarWChar, 50);
        tableCustomer.Columns.Append("Email", ADOX.DataTypeEnum.adVarWChar, 50);
        tableCustomer.Columns.Append("TelNumber", ADOX.DataTypeEnum.adVarWChar, 32);
        tableCustomer.Columns.Append("Fax", ADOX.DataTypeEnum.adVarWChar, 32);
        tableCustomer.Columns.Append("Street", ADOX.DataTypeEnum.adVarWChar, 50);
        tableCustomer.Columns.Append("PostalCode", ADOX.DataTypeEnum.adInteger, 10);
        tableCustomer.Columns.Append("City", ADOX.DataTypeEnum.adVarWChar, 50);
        tableCustomer.Columns.Append("AdressCounter", ADOX.DataTypeEnum.adSmallInt);

        tableAddresses.Name = "Addresses";
        tableAddresses.Columns.Append("Address_ID", ADOX.DataTypeEnum.adInteger);
        tableAddresses.Keys.Append("PrimaryKEy", KeyTypeEnum.adKeyPrimary, "Address_ID");
        //tableAddresses.Columns.Append("Customer_ID", ADOX.DataTypeEnum.adInteger);            
        //tableAddresses.Keys.Append("ForeignKey", KeyTypeEnum.adKeyForeign, "Customer_ID");  ---> here is the Exception
        tableAddresses.Columns.Append("Street", ADOX.DataTypeEnum.adVarWChar, 50);
        tableAddresses.Columns.Append("PostalCode", ADOX.DataTypeEnum.adInteger, 10);
        tableAddresses.Columns.Append("City", ADOX.DataTypeEnum.adVarWChar, 50);

        try
        {
            cat.Create("Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + Application.StartupPath + "\\Customers.mdb" + "; Jet OLEDB:Engine Type=5");
            cat.Tables.Append(tableCustomer);
            cat.Tables.Append(tableAddresses);

            //Now Close the database
            ADODB.Connection con = cat.ActiveConnection as ADODB.Connection;
            if (con != null)
                con.Close();


            result = true;
        }
        catch (Exception ex)
        {
            result = false;
        }
        finally
        {
            if (!result)
            {
                ADODB.Connection con = cat.ActiveConnection as ADODB.Connection;
                if (con != null)
                    con.Close();
                File.Delete(Application.StartupPath + "\\Customers.accdb");
            }                  
        }
        cat = null;
        return result;
    }

如果像下面这样尝试antoher方法(在用上一种方法创建数据库之后打开数据库)，它也不能工作：

private static bool addForeignKey()
    {
        bool retValue = true;

        ADODB.Connection con = new Connection();
        Key kyForeign = new Key();
        Catalog cat = new Catalog();


        kyForeign.Name = "test";
        kyForeign.Type = KeyTypeEnum.adKeyForeign;
        kyForeign.RelatedTable = "Customer";
        kyForeign.Columns.Append("CustomerID", ADOX.DataTypeEnum.adInteger);
        kyForeign.Columns["CustomerID"].RelatedColumn = "Customer_ID";
        try
        {   
            con.Open("Provider='Microsoft.JET.OLEDB.4.0';Data source ='"
               + Application.StartupPath + "\\Customers.mdb';");
            cat.ActiveConnection = con;
            cat.Tables["Addresses"].Keys.Append(kyForeign, KeyTypeEnum.adKeyForeign, ADOX.DataTypeEnum.adInteger); // here comes the Exception
        }
        catch
        {
            retValue = false;
        }
        finally
        {
            if(retValue)
            {
                if (con != null)
                    con.Close();
            }
        }
        return retValue;
    }

我找不到一个好的文档为adox的代码示例，这就是为什么我不知道如何解决这个问题？先期

Answer 1

问题是您没有填充RelatedTable和RelatedColumn参数。将第一段代码中的注释行替换为：

        tableAddresses.Columns.Append("Customer_ID", ADOX.DataTypeEnum.adInteger); 
        tableAddresses.Keys.Append("ForeignKey", ADOX.KeyTypeEnum.adKeyForeign, "Customer_ID", "Customer", "Customer_ID");