Querying Data
After Connecting, you can allocate a statement handle and execute the statement.
SELECT Procedure
Use SQLExecDirect to execute the statement and SQLFetch to fetch the records. You can use SQLBindCol to bind variables to columns in the result set. The numbering of the result set columns starts at 1.
SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv); SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0); SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc); SQLDriverConnect(hdbc, 0, (SQLCHAR*)"Dsn=CData PayPal Source", SQL_NTS, 0, 0, 0, 0); SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt); SQLExecDirect(hstmt, (SQLCHAR*)"SELECT State FROM Payments WHERE CreateTime > '2016-01-15'", SQL_NTS); SQLCHAR sState[20] = {0}; SQLLEN cbState = 0; SQLBindCol(hstmt, 1, SQL_C_CHAR, sState, 20, &cbState); SQLRETURN retcode = SQLFetch(hstmt); if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) { ... }
Iterating over the Results
You can use SQLGetData to get values while iterating through a cursor. To iterate over the results, use SQLFetch to fetch rows and SQLGetData to retrieve the column values.
SQLHENV henv; SQLHDBC hdbc; SQLHSTMT hstmt; char sId[255] = {0}; SQLLEN cbId = 0; if (SQLAllocHandle(SQL_HANDLE_ENV, 0 ,&henv) == SQL_SUCCESS) { SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0); if (SQLAllocHandle(SQL_HANDLE_DBC, henv ,&hdbc) == SQL_SUCCESS) { if (SQLConnect(hdbc, "CData PayPal Source", SQL_NTS, 0, 0, 0, 0) == SQL_SUCCESS) { if (SQLAllocHandle(SQL_HANDLE_STMT, hdbc ,&hstmt) == SQL_SUCCESS) { if (SQLExecDirect(hstmt, "SELECT Id FROM Payments WHERE CreateTime > '2016-01-15'", SQL_NTS) == SQL_SUCCESS) { while(SQLFetch(hstmt) == SQL_SUCCESS) { if (SQLGetData(hstmt, 1, SQL_C_CHAR, (SQLPOINTER)sId, 255, &cbId) == SQL_SUCCESS) { printf("Id: %s\n", sId); } } } SQLFreeHandle(SQL_HANDLE_STMT, hstmt); } SQLDisconnect(hdbc); } SQLFreeHandle(SQL_HANDLE_DBC, hdbc); } SQLFreeHandle(SQL_HANDLE_ENV, henv); }