Fix handling of NULL values when reading from tables.

  modified:   storage/connect/tabodbc.cpp
  modified:   storage/connect/value.h

storage/connect/tabodbc.cpp

@@ -1268,6 +1268,10 @@ void ODBCCOL::ReadColumn(PGLOBAL g)
 
   } // endif Buf_Type
 
+  // Handle null values
+  if (Value->IsZero())
+    Value->SetNull(Nullable);
+
   if (trace) {
     char buf[64];
 
@@ -1393,7 +1397,7 @@ void ODBCCOL::WriteColumn(PGLOBAL g)
 /* -------------------------- Class TDBXDBC -------------------------- */
 
 /***********************************************************************/
-/*  Implementation of the TDBODBC class.                               */
+/*  Implementation of the TDBXDBC class.                               */
 /***********************************************************************/
 TDBXDBC::TDBXDBC(PODEF tdp) : TDBODBC(tdp)
 {

storage/connect/value.h

@@ -360,14 +360,9 @@ class DllExport DTVAL : public TYPVAL<int> {
  public:
   // Constructors
   DTVAL(PGLOBAL g, int n, int p, PSZ fmt);
-//DTVAL(PGLOBAL g, PSZ s, int n);
-//DTVAL(PGLOBAL g, short i);
   DTVAL(int n);
-//DTVAL(PGLOBAL g, longlong n);
-//DTVAL(PGLOBAL g, double f);
 
   // Implementation
-  virtual bool   IsZero(void) {return Null;}
   virtual bool   SetValue_pval(PVAL valp, bool chktype);
   virtual bool   SetValue_char(char *p, int n);
   virtual void   SetValue_psz(PSZ s);