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？

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.我不能进行简单的字符串比较,因为属性可以以不同的方式布局,但仍然代表相同的连接.

在我为此写下自己的比较之前,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

您可以使用该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,这些未初始化的数据源对象上you can query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.这将返回一个DBPROPSET结构,其中包含一个DBPROP元素数组(属性).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.

IsSameConnStr如果连接字符串相等,则以下函数返回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,您可以指定ConnectionStringto TADOConnection(不实际连接到DB)并使用TADOConnection.Properties集合(集合项目ADOInt.Property_),例如:

ADOConnection.Properties.Get_Item('Data Source')

您应该比较特定属性,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.如:
Provider,Data Source,Initial Catalog,User ID\ Password(可选).

有迹象表明,你可能要依赖于供应商如忽视了许多特性:
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;

在连接到数据库ConnectionString 之后 ,可能会有更多属性添加到/更改TADOConnection,因此您需要考虑这一点.