This example illustrates the steps needed to perform a basic retrieval. The following grid shows a five dimensional template with one datapoint illustrated.
The following code fragment shows how the data structures are setup and the function calls that are needed to perform the retrieval.
/* This function allocates the necessary data to send to the server */
ESSG_PPDATA_T AllocTwoDims(ESSG_ULONG_T ulRows, ESSG_ULONG_T ulCols)
{
ESSG_PPDATA_T ppTemp;
ESSG_ULONG_T ulIndex;
if(ulRows)
ppTemp = (ESSG_PPDATA_T) malloc(sizeof(ESSG_DATA_T*) * ulRows);
if(ppTemp == NULL)
return ppTemp;
memset(ppTemp, 0, (sizeof(ESSG_PDATA_T) * ulRows));
for (ulIndex = 0; ulIndex < ulRows; ulIndex++)
{
ppTemp[ulIndex] = (ESSG_PDATA_T)malloc(sizeof(ESSG_DATA_T) * ulCols);
if(ppTemp[ulIndex])
memset(ppTemp[ulIndex], 0, (sizeof(ESSG_DATA_T) * ulCols));
}
return ppTemp;
}
/* This function frees the memory allocated by AllocTwoDims */
void FreeTwoDim(ESSG_PPDATA_T ppDataToFree, ESS_ULONG_T ulRows)
{
ESS_ULONG_T ulIndex;
for (ulIndex = 0; ulIndex < ulRows; ulIndex++)
{
if(ppDataToFree[ulIndex]->usType == ESSG_DT_STRING)
{
free(ppDataToFree[ulIndex]->Value.pszStr);
}
free(ppDataToFree[ulIndex]);
}
free(ppDataToFree);
}
/* This function builds a table based on the above grid. */
/* Note: The items in the grid are hard coded. */
ESSG_PPDATA_T BuildTable(ESSG_PRANGE_T pRange)
{
ESSG_PPDATA_T ppTable;
ESS_ULONG_T ulRow, ulCol;
/* Your code would probably not be hard-coded here... */
pRange->ulRowStart = 0;
pRange->ulColumnStart = 0;
pRange->ulNumRows = 2;
pRange->ulNumColumns = 5;
ppTable = AllocTwoDims(2, 5);
/* ROW 1 */
ppTable[0][0].usType = ESSG_DT_BLANK;
ppTable[0][1].usType = ESSG_DT_BLANK;
ppTable[0][2].usType = ESSG_DT_STRING;
/* Some compilers allow you to specify \p to indicate */
/* the length of the string */
ppTable[0][2].Value.pszStr = "\pYear";
ppTable[0][3].usType = ESSG_DT_STRING;
ppTable[0][3].Value.pszStr = "\pProduct";
ppTable[0][4].usType = ESSG_DT_STRING;
ppTable[0][4].Value.pszStr = "\pMarket";
/* ROW 2 */
ppTable[1][0].usType = ESSG_DT_STRING;
ppTable[1][0].Value.pszStr = "\pActual";
ppTable[1][1].usType = ESSG_DT_STRING;
ppTable[1][1].Value.pszStr = "\pSales";
ppTable[1][2].usType = ESSG_DT_DOUBLE;
ppTable[1][2].dblData = 123.45;
ppTable[1][3].usType = ESSG_DT_BLANK;
ppTable[1][4].usType = ESSG_DT_BLANK;
return (ppTable);
}
/* This function makes the necessary calls to the */
/* EGAPI to perform a basic retrieval. */
/* NOTE: This example does not show the */
/* initialization of the EGAPI or the grid. */
/* Also, the hGrid is assumed to be external. */
void CallEGAPI(void)
{
ESSG_PPDATA_T ppDataIn,
ESSG_PPDATA_T ppDataOut;
ESSG_RANGE_T rRangeDataIn,rRangeDataOut;
ESSG_STS_T sts;
ESSG_ULONG_T ulRow, ulCol;
ESSG_USHORT_T usState;
/* Connect the grid to a database on the server */
sts = EssGConnect(hGrid, "Server", "User", "Password",
"App", "Db", ESSG_CONNECT_DEFAULT);
if (sts == 0)
{
ppDataIn = BuildTable(rRangeDatain);
/* Start the retrieve operation */
sts = EssGBeginRetrieve(hGrid, ESSG_RET_RETRIEVE);
}
if (sts == 0)
{
/* Send the entire grid to define the query */
sts = EssGSendRows(hGrid, rRangeDatain, ppDataIn);
}
if (sts == 0)
{
/* We're done sending rows, perform the retrieval */
sts = EssGPerformOperation(hGrid, 0);
/* Free the data we built */
FreeTwoDim(ppDataIn, rRangeDataIn.ulNumRows);
}
if (sts == 0)
{
/* Determine the results of the retrieve and how much data
* is being returned.
*/
sts = EssGGetResults(hGrid, 0, rRangeDataOut, usState);
}
if (sts == 0)
{
/* Get all of the data */
sts = EssGGetRows(hGrid,0, rRangeDataOut,
rRangeDateOut, ppDataOut);
}
if (sts == 0)
{
/* Interate though the data ... */
/* First the rows */
for (ulRow = rRangeDataOut.ulRowStart;
ulRow < rRangeDataOut.ulNumRows;
ulRow++)
{
/* Then the columns */
for (ulCol = rRangeDataOut.ulColumnStart;
ulCol < rRangeDataOut.ulNumColumns;
ulCol++)
{
/* Here's a cell ... just render it. */
switch (ppDataOut[ulRow][ulCol].usType)
{
case (ESSG_DT_STRING):
DisplayString(ppDataOut[ulRow][ulCol].Value.pszStr);
break;
case (ESSG_DT_LONG):
DisplayValue(ppDataOut[ulRow][ulCol].Value.lData);
break;
case (ESSG_DT_DOUBLE):
DisplayValue(ppDataOut[ulRow][ulCol].Value.dblData);
break;
case (ESSG_DT_BLANK):
DisplayBlank();
break;
case (ESSG_DT_MISSING):
DisplayMissing();
break;
case (ESSG_DT_ZERO):
DisplayValue(0);
break;
case (ESSG_DT_NOACCESS):
DisplayNoAccess();
break;
case (ESSG_DT_MEMBEREX):
DisplayString(ppDataOut[ulRow][ulCol].Value.pszStr+1);
break;
default:
DisplayOops();
break;
}
}
}
/* Tell the API we don't care about this request any more */
EssGEndOperation(hGrid, 0);
/* Free the data returned */
EssGFreeRows(hGrid, rRangeDataOut, ppDataOut);
}
/* Disconnect if you wish */
EssGDisconnect(hGrid, 0);
}