TeslaRel410/BORLAND/BDE/EXAMPLES/SNIPIT/TBRSTRCT.C

// BDE - (C) Copyright 1995 by Borland International

// tbrstrct.c
#include "snipit.h"

static const char szTblName[]       = "contacts";
static const char szRstrctTblName[] = "rstrct";
static const char szTblType[]       = szPARADOX;

#define NUMOFFIELDS 4

static DBIResult getFieldDescs(hDBICur hCur, UINT16 *uNumFields,
                               FLDDesc **fldDesc);
static DBIResult changeFieldDescs(UINT16 *uNumFields, FLDDesc *fldDesc,
                                  FLDDesc *fldDescriptor, CROpType *ecrFldOp);

//=====================================================================
//  Function:
//          TBRestructure();
//
//  Description:
//          This example shows how to change the characteristics of a
//          table, adding, dropping and changing fields.
//
//          The following steps are followed:
//              Getting the existing field descriptors
//              Modifying the field descriptors to the new table structure
//              Initializing the CRTblDesc (create table descriptor)
//              Restructuring the table
//=====================================================================
void
TBRestructure (void)
{
    hDBIDb      hDb;            // Handle to the database
    hDBICur     hCur;           // Handle to the table
    CRTblDesc   crTblDesc;      // Table descriptor
    UINT16      uNumFields;     // Number of fields
    UINT16      uNumOfRecs = 5; // Nunmber of records to display
    FLDDesc     *fldDesc;       // Pointer to the field descriptors
    FLDDesc     fldDescriptor[NUMOFFIELDS]; // Field descriptor
    CROpType    ecrFldOp[NUMOFFIELDS];      // Field operations
    DBIResult   rslt;           // Return value from IDAPI functions
    DBIPATH     szKeyViol = "KEYVIOL"; // Name for the key violation table

    Screen("*** Restructure Example ***\r\n");

    BREAK_IN_DEBUGGER();

    Screen("    Initializing IDAPI...");
    if (InitAndConnect(&hDb) != DBIERR_NONE)
    {                                        
        Screen("*** End of Example ***");
        return;
    }

    Screen("    Setting the database directory... ");
    rslt = DbiSetDirectory(hDb, (pCHAR) szTblDirectory);
    ChkRslt(rslt, "SetDirectory");

    Screen("    Open the %s table....", szTblName);
    rslt = DbiOpenTable(hDb, (pCHAR) szTblName, (pCHAR) szTblType,
                        NULL, NULL, 0, dbiREADWRITE, dbiOPENSHARED,
                        xltFIELD, FALSE, NULL, &hCur);
    if (ChkRslt(rslt, "OpenTable") != DBIERR_NONE)
    {
        CloseDbAndExit(&hDb);
        Screen("\r\n*** End of Example ***");
        return;
    }

    rslt = DbiSetToBegin(hCur);
    ChkRslt(rslt, "SetToBegin");

    Screen("    Display the first %u records of the %s table...",
           uNumOfRecs, szTblName);
    DisplayTable(hCur, uNumOfRecs);

    // Get the field descriptors for the existing table.
    if (getFieldDescs(hCur, &uNumFields, &fldDesc) != DBIERR_NONE)
    {
        rslt = DbiCloseCursor(&hCur);
        ChkRslt(rslt, "CloseCursor");
        CloseDbAndExit(&hDb);
        Screen("\r\n*** End of Example ***");
        return;
    }

    Screen("\r\n    Close the %s table...", szTblName);
    DbiCloseCursor(&hCur);

    Screen("    Initialize the table descriptor...");
    memset(&crTblDesc, 0, sizeof(CRTblDesc));
    strcpy(crTblDesc.szTblName, szTblName);
    strcpy(crTblDesc.szTblType, szTblType);
    crTblDesc.bPack         = TRUE;
    changeFieldDescs(&uNumFields, fldDesc, fldDescriptor, ecrFldOp);
    crTblDesc.iFldCount     = uNumFields;
    crTblDesc.pecrFldOp     = ecrFldOp;
    crTblDesc.pfldDesc      = fldDescriptor;

    Screen("    Restructure the %s table to the %s table...",
           szTblName, szRstrctTblName);
    rslt = DbiDoRestructure(hDb, 1, &crTblDesc, (pCHAR) szRstrctTblName,
                            szKeyViol, NULL, FALSE);
    if (ChkRslt(rslt, "DoRestructure") != DBIERR_NONE)
    {
        free(fldDesc);
        CloseDbAndExit(&hDb);
        Screen("\r\n*** End of Example ***");
        return;
    }

    Screen("    Open the %s table...", szRstrctTblName);
    rslt = DbiOpenTable(hDb, (pCHAR) szRstrctTblName, (pCHAR) szTblType,
                        NULL, NULL, 0, dbiREADWRITE, dbiOPENSHARED,
                        xltFIELD, FALSE, NULL, &hCur);
    if (ChkRslt(rslt, "OpenTable") != DBIERR_NONE)
    {
        free(fldDesc);
        rslt = DbiDeleteTable(hDb, (pCHAR) szRstrctTblName, (pCHAR) szTblType);
        ChkRslt(rslt, "DeleteTable");
        CloseDbAndExit(&hDb);
        Screen("\r\n*** End of Example ***");
        return;
    }

    rslt = DbiSetToBegin(hCur);
    ChkRslt(rslt, "SetToBegin");

    Screen("    Display the first %u records of the %s table...",
           uNumOfRecs, szRstrctTblName);
    DisplayTable(hCur, uNumOfRecs);

    Screen("\r\n    Close the %s table...", szRstrctTblName);
    rslt = DbiCloseCursor(&hCur);
    ChkRslt(rslt, "CloseCursor");

    Screen("    Delete the %s table...", szRstrctTblName);
    rslt = DbiDeleteTable(hDb, (pCHAR) szRstrctTblName, (pCHAR) szTblType);
    ChkRslt(rslt, "DeleteTable");

    free(fldDesc);

    Screen("    Close the database and exit IDAPI...");
    CloseDbAndExit(&hDb);

    Screen("\r\n*** End of Example ***");
}

//===============================================================
//  Function:
//          getFieldDescs(hCur, *uNumFields, **fldDesc)
//
//  Input:  hCur            - Handle to the cursor
//          uNumFields      - Number of fields in the field descriptor
//                            (Returned)
//          fldDesc         - Existing field descriptor (Input)
//
//  Return: IDAPI return code
//
//  Description:
//          This function gets the field descriptor for an existing cursor.
//================================================================
DBIResult
getFieldDescs (hDBICur hCur, UINT16 *uNumFields, FLDDesc **fldDesc)
{
    DBIResult   rslt;       // Return value from IDAPI functions
    CURProps    curProps;   // Properties of the table

    // Change the translation mode to xltNONE to get the physical 
    //   field descriptors.
    rslt = DbiSetProp(hCur, curXLTMODE, xltNONE);
    ChkRslt(rslt, "SetProp");

    rslt = DbiGetCursorProps(hCur, &curProps);
    if (ChkRslt(rslt, "GetCursorProps") != DBIERR_NONE)
    {
        return rslt;
    }

    *uNumFields = curProps.iFields;

    *fldDesc = (FLDDesc *) malloc(curProps.iFields * sizeof(FLDDesc));
    if (fldDesc == NULL)
    {
        return DBIERR_NOMEMORY;
    }

    rslt = DbiGetFieldDescs(hCur, *fldDesc);
    if (ChkRslt(rslt, "GetFIeldDescs") != DBIERR_NONE)
    {
        return rslt;
    }

    // Change the translation mode back to xltFIELD.
    rslt = DbiSetProp(hCur, curXLTMODE, xltFIELD);
    ChkRslt(rslt, "SetProp");

    return DBIERR_NONE;
}

//===============================================================
//  Function:
//          changeFieldDescs(UINT16 *uNumFields, FLDDesc *fldDesc,
//                           FLDDesc *fldDescriptor, CROpType *ecrFldOp);
//
//  Input:  uNumFields      - Number of fields in the existing field
//                            descriptor. Also returns the number of
//                            fields in the new field descriptor
//                            (Input and Returned)
//          fldDesc         - Existing field descriptor (Input)
//          fldDescriptor   - New field descriptor to use (Returned)
//          ecrFldOp        - Array of operations on the fields in
//                            fldDescriptor (Returned)
//
//  Return: IDAPI return code
//
//  Description:
//          This function sets up the field structure for the new table.
//================================================================
DBIResult
changeFieldDescs (UINT16 *uNumFields, FLDDesc *fldDesc,
                  FLDDesc *fldDescriptor, CROpType *ecrFldOp)
{
    UINT16      i;      // Loop Counter
    UINT16      uField; // Number of the field

    uField = 0;
    
    for (i=0; i < *uNumFields; i++)
    {
        // Keep the "Last Name" field as is.
        if (! strcmp(fldDesc[i].szName, "Last Name"))
        {
            fldDescriptor[uField] = fldDesc[i];
            ecrFldOp[uField] = crNOOP;
            uField++;
        }

        // Change the "First Name" field.
        if (! strcmp(fldDesc[i].szName, "First Name"))
        {
            fldDescriptor[uField] = fldDesc[i];
            strcpy(fldDescriptor[uField].szName, "First");
            ecrFldOp[uField] = crMODIFY;
            uField++;
        }

        // Move the "Phone" Field.
        if (! strcmp(fldDesc[i].szName, "Phone"))
        {
            fldDescriptor[uField] = fldDesc[i];
            ecrFldOp[uField] = crCOPY;
            uField++;
        }
    }

    // Make certain that there is enough space in the field descriptor
    //   for a new field.
    if (uField < *uNumFields)
    {
        // Add the "Age" field.
        fldDescriptor[uField].iFldNum        = 0;
        strcpy(fldDescriptor[uField].szName, "Age");
        fldDescriptor[uField].iFldType       = fldPDXSHORT;
        fldDescriptor[uField].iSubType       = 0;
        fldDescriptor[uField].iUnits1        = 0;
        fldDescriptor[uField].iUnits2        = 0;
        fldDescriptor[uField].iOffset        = 0;
        fldDescriptor[uField].iLen           = 0;
        fldDescriptor[uField].iNullOffset    = 0;
        fldDescriptor[uField].efldvVchk      = fldvNOCHECKS;
        fldDescriptor[uField].efldrRights    = fldrREADWRITE;

        ecrFldOp[uField] = crADD;

        uField++;
    }
    
    *uNumFields = uField;

    return DBIERR_NONE;
}