Re: Relational vs. PICK/Object DBMS

Below is a solution using XDb1/TDM.
See www.xdb1.com/Example/Ex109.asp for additional info. See www.xdb1.com/Example/Ex108.asp for similar problem/solution.

void Example109()
{
// Create wig class

    int* pWig = T_create();
    T_relate(&pWig, rCls, &pThing_g);
    T_Name_relate(&pWig, _T("wig"));

// Create coat class

    int* pCoat = T_create();
    T_relate(&pCoat, rCls, &pThing_g);
    T_Name_relate(&pCoat, _T("coat"));

// Create color class

    int* pColor = T_create();
    T_relate(&pColor, rCls, &pThing_g);
    T_Name_relate(&pColor, _T("color"));

// Create texture class

    int* pTexture = T_create();
    T_relate(&pTexture, rCls, &pThing_g);     T_Name_relate(&pTexture, _T("texture"));

// Create material class

    int* pMaterial = T_create();
    T_relate(&pMaterial, rCls, &pThing_g);     T_Name_relate(&pMaterial, _T("material"));

// Create wig1
// Its color is red.

    int* pWig1 = T_create();

    T_relate(&pWig1, rCls, &pWig);
    T_Name_relate(&pWig1, _T("wig1"));
    T_Val_relate(&pWig1, &pColor, _T("red"));

// Create wig2
// Its color is red, green
// AND texture is soft AND material is nylon.
    int* pWig2 = T_create();

    T_relate(&pWig2, rCls, &pWig);
    T_Name_relate(&pWig2, _T("wig2"));
    T_Val_relate(&pWig2, &pColor, _T("red"));
    T_Val_relate(&pWig2, &pColor, _T("green"));
    T_Val_relate(&pWig2, &pTexture, _T("soft"));
    T_Val_relate(&pWig2, &pMaterial, _T("nylon"));

// Create wig3
// Its texture is soft AND material is jute.
    int* pWig3 = T_create();

    T_relate(&pWig3, rCls, &pWig);
    T_Name_relate(&pWig3, _T("wig3"));
    T_Val_relate(&pWig3, &pTexture, _T("soft"));
    T_Val_relate(&pWig3, &pMaterial, _T("jute"));

// Create coat1
// Its color is red.

    int* pCoat1 = T_create();

    T_relate(&pCoat1, rCls, &pCoat);
    T_Name_relate(&pCoat1, _T("coat1"));
    T_Val_relate(&pCoat1, &pColor, _T("red"));

// Create coat2
// Its texture is soft AND material is cotton.
    int* pCoat2 = T_create();

    T_relate(&pCoat2, rCls, &pCoat);
    T_Name_relate(&pCoat2, _T("coat2"));
    T_Val_relate(&pCoat2, &pTexture, _T("soft"));
    T_Val_relate(&pCoat2, &pMaterial, _T("cotton"));

// Create coat3
// Its color is green AND texture is smooth, supple.
    int* pCoat3 = T_create();

    T_relate(&pCoat3, rCls, &pCoat);
    T_Name_relate(&pCoat3, _T("coat3"));
    T_Val_relate(&pCoat3, &pColor, _T("green"));
    T_Val_relate(&pCoat3, &pTexture, _T("smooth"));
    T_Val_relate(&pCoat3, &pTexture, _T("supple"));

// Create a relational expression
// to find things related to color AND texture
    TCHAR sExpr[kNmSz_g+1] = _T("((color)) ((texture))");

// Prepare relational expression

    #define aSz 255
    int* pExpr[aSz+1] = {NULL};
    if (X_parse_r(sExpr, pExpr, aSz)) {return;}

// Loop thru things satisfying expression
// and print the found thing's full name.
// The loop below prints the following three lines
// "((wig))(wig2)(((color))(red))(((color))(green))(((texture))(soft))(((material))(nylon))"
// "((wig))(wig2)(((color))(red))(((color))(green))(((texture))(soft))(((material))(nylon))"
// "((coat))(coat3)(((color))(green))(((texture))(smooth))(((texture))(supple))"
// Note: wig2 is printed twice because
// the query routes via the two colors of wig2: red and green
    while (int* pT=X(pExpr)){

      TCHAR sName[kNmSz_g+1] = _T("");
      T_Name_get(pT, sName, kNmSz_g, TRUE);
      TRACE(_T("%s\n"), sName);

// Given wig1, print its info
// Prints "((wig))(wig1)(((color))(red))"
    TCHAR sName[kNmSz_g+1] = _T("");
    T_Name_get(pWig1, sName, kNmSz_g, TRUE);     TRACE(_T("%s\n"), sName);

// Given wig2, print its info
// Prints "((wig))(wig2)(((color))(red))(((color))(green))(((texture))(soft))(((material))(nylon))"
    _tcscpy(sName, _T(""));
    T_Name_get(pWig2, sName, kNmSz_g, TRUE);     TRACE(_T("%s\n"), sName);

// Given wig3, print its properties/values using alternate method
// "wig3's name is wig3."
// "wig3's texture is soft."
// "wig3's material is jute."
// Loop thru wig3's relations

    int* pR = pWig3;
    while (*(++pR)){

      // If relation is to a value
        if (rIs == R_Type_get(pR)){
          // Get value
            int* pVal = R_Dest(pR);

          // Get value's Cls (same a property)
            int* pProp = T_R_Xth(pVal, rCls);

          // Print "thingX's propY is valX."
            TCHAR sTh[kNmSz_g+1] = _T("");
            T_Name_get(pWig3, sTh, kNmSz_g);

            TCHAR sProp[kNmSz_g+1] = _T("");
            T_Name_get(pProp, sProp, kNmSz_g);

            TCHAR sVal[kNmSz_g+1] = _T("");
            T_Name_get(pVal, sVal, kNmSz_g);

            TCHAR sSent[3*kNmSz_g+1] = _T("");
            _stprintf(sSent, _T("%s's %s is %s."), sTh, sProp, sVal);
            TRACE(_T("%s\n"), sSent);
        }

> What happens to the solution if the set of all attributes is large > but the set of attributes recorded for any entity vary from none to all?

The problems that arise from the above situation in RDM don't apply to XDb1/TDM. Received on Tue Apr 27 2004 - 07:24:14 CEST