Question

我需要能够将两个不同的连接字符串进行比较，并确定它们是否是相同的信息。我不能做一个简单的字符串比较，因为属性可以不同的方式布局，但仍然代表相同的连接。

在我开始编写自己的比较之前，是否已经可以做到这一点？

我已经找到了一种方法，我找不到任何关于此的内容。

Answer 1

您可以使用IDataInitialize::GetDataSource方法，该方法从给定的连接字符串返回未初始化的数据源对象。由于此方法返回指向IUnknown类型的数据源对象的指针，因此无法直接比较为两个比较连接字符串获取的对象。但是，you can query这些未初始化的数据源对象上的IDBProperties接口使您可以访问给定提供程序支持的所有属性。

要获取属性集，您需要使用IDBProperties::GetProperties方法。这将返回DBPROPSET结构，其中包含DBPROP个元素（属性）数组。然后，您将简单地迭代此数组，并以您需要的方式比较这两个数据源对象的属性。

如果连接字符串相等，则以下IsSameConnStr函数返回True，否则返回False。请注意，使用的属性值比较不区分大小写，但DBPROP_AUTH_PASSWORD属性除外，它与区分大小写进行比较：

uses
  ActiveX, ComObj, OleDB;

function IsSameVarWideStr(const AValue1, AValue2: OleVariant;
  ACaseSensitive: Boolean = False): Boolean;
begin
  Result := VarType(AValue1) = VarType(AValue2);
  if Result then
  begin
    if ACaseSensitive then
      Result := WideCompareStr(VarToWideStr(AValue1),
        VarToWideStr(AValue2)) = 0
    else
      Result := WideCompareText(VarToWideStr(AValue1),
        VarToWideStr(AValue2)) = 0;
  end;
end;

function IsSameConnStr(const AConnStr1, AConnStr2: WideString): Boolean;
var
  I: Integer;
  DataSrc1: IUnknown;
  DataSrc2: IUnknown;
  DataInit: IDataInitialize;
  PropSet1: PDBPropSet;
  PropSet2: PDBPropSet;
  PropSetCnt1: ULONG;
  PropSetCnt2: ULONG;
  Properties1: IDBProperties;
  Properties2: IDBProperties;
const
  DBPROP_AUTH_PASSWORD = $00000009;
begin
  // first check if the input connection strings aren't exactly the same
  Result := CompareStr(AConnStr1, AConnStr2) = 0;
  // if they are not same, then...
  if not Result then
  begin
    // create IDataInitialize object instance
    OleCheck(CoCreateInstance(CLSID_DataLinks, nil, CLSCTX_INPROC_SERVER or
      CLSCTX_LOCAL_SERVER, IID_IDataInitialize, DataInit));
    // get data source objects for both input connection strings
    OleCheck(DataInit.GetDataSource(nil, CLSCTX_INPROC_SERVER,
      PWideChar(AConnStr1), IUnknown, DataSrc1));
    OleCheck(DataInit.GetDataSource(nil, CLSCTX_INPROC_SERVER,
      PWideChar(AConnStr2), IUnknown, DataSrc2));
    // query for IDBProperties objects of the data source objects
    if Succeeded(DataSrc1.QueryInterface(IID_IDBProperties, Properties1)) and
      Succeeded(DataSrc2.QueryInterface(IID_IDBProperties, Properties2)) then
    begin
      // get properties of data source objects
      OleCheck(Properties1.GetProperties(0, nil, PropSetCnt1, PropSet1));
      OleCheck(Properties2.GetProperties(0, nil, PropSetCnt2, PropSet2));
      try
        // same DB provider will have the same set of initialization properties,
        // so the first check might be the property count, if that differs, then
        // at least DB provider is different, so if this equals, then...
        if PropSetCnt1 = PropSetCnt2 then
        begin
          // initialize positive result
          Result := True;
          // iterate all the properties
          for I := 0 to PropSet1.cProperties - 1 do
          begin
            // check if we're comparing the same property and if so, compare the
            // property values; for password property compare the value with case
            // sensitivity, for all the others case insensitively; if any of this
            // doesn't match, we're done with False result and we can exit
            if (PropSet1.rgProperties[I].dwPropertyID <>
              PropSet2.rgProperties[I].dwPropertyID) or
              not IsSameVarWideStr(PropSet1.rgProperties[I].vValue,
              PropSet2.rgProperties[I].vValue,
              PropSet1.rgProperties[I].dwPropertyID = DBPROP_AUTH_PASSWORD) then
            begin
              Result := False;
              Break;
            end;
          end;
        end;
      finally
        // release the property sets; note that you should avoid this common
        // try..finally block and that you should free also each property array
        // element by using IMalloc::Free; why I've used CoTaskMemFree see this
        // question http://stackoverflow.com/q/3079508/960757
        CoTaskMemFree(PropSet1);
        CoTaskMemFree(PropSet2);
      end;
    end;
  end;
end;

我认为用法很明确，所以我宁愿提一些连接字符串的结果：

IsSameConnStr = True
AConnStr1: Provider=MSDASQL.1;Persist Security Info=True;Data Source=datasource
AConnStr2: Provider=MSDASQL.1;Persist Security Info=True;Data Source=DATASOURCE

IsSameConnStr = True
AConnStr1: Provider=MSDASQL.1;Data Source=datasource;Persist Security Info=True
AConnStr2: Provider=MSDASQL.1;Persist Security Info=True;Data Source=DATASOURCE

IsSameConnStr = True
AConnStr1: Provider=MSDASQL.1;Password=PASSWORD;Data Source=datasource;Persist Security Info=True
AConnStr2: Provider=MSDASQL.1;Data Source=DATASOURCE;Password=PASSWORD;Persist Security Info=True

IsSameConnStr = False - password differs in case sensitivity
AConnStr1: Provider=MSDASQL.1;Password=PASSWORd;Data Source=datasource;Persist Security Info=True
AConnStr2: Provider=MSDASQL.1;Data Source=DATASOURCE;Password=PASSWORD;Persist Security Info=True

Answer 2

要获取ConnectionString属性的集合，您可以将ConnectionString分配给TADOConnection（不实际连接到数据库）并使用TADOConnection.Properties集合（集合项）是ADOInt.Property_）例如：

ADOConnection.Properties.Get_Item('Data Source')

您应该比较特定的属性，以确定是否通过特定提供程序将连接设置为特定数据存储。例如： -
Provider，Data Source，Initial Catalog，User ID \ Password（可选）。

根据提供商的不同，您可能希望忽略许多属性，例如：
Workstation ID，Persist Security Info，Use Procedure for Prepare，Auto Translate等......

以下是如何迭代TADOConnection属性集合的示例：

var
  ADOConnection: TADOConnection;
  PropName, PropValue: WideString;
  I: Integer;

  ADOConnection := TADOConnection.Create(nil);
  try
    ADOConnection.ConnectionString := 'Provider=MSDASQL.1;Password=secret;Data Source=127.0.0.1;User ID=user;Initial Catalog=mycatalog';
    for I := 0 to ADOConnection.Properties.Count - 1 do
    begin
      // Properties.Item[I] is ADOInt.Property_
      PropName := ADOConnection.Properties.Item[I].Name;
      PropValue := VarToWideStr(ADOConnection.Properties.Item[I].Value);
      ShowMessage(Format('%s=%s', [PropName, PropValue]));
    end;
  finally
    ADOConnection.Free;
  end;

在 ConnectionString连接到数据库后，TADOConnection 中可能会添加/更改更多属性，因此您需要考虑这一点。

是否有任何简单的方法来比较连接字符串而不自己解析它？

2 个答案: