Index: ext/session/session1.test
==================================================================
--- ext/session/session1.test
+++ ext/session/session1.test
@@ -567,7 +567,19 @@
   {INSERT $tblname 0 X. {} {t uvw t abc}}
   {DELETE $tblname 0 X. {t xyz t def} {}}
 "
 do_test 10.1.4 { S delete } {}
 
+#-------------------------------------------------------------------------
+# Test the effect of updating a column from 0.0 to 0.0.
+#
+reset_db
+do_execsql_test 11.1 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b REAL);
+  INSERT INTO t1 VALUES(1, 0.0);
+}
+do_iterator_test 11.2 * {
+  UPDATE t1 SET b = 0.0;
+} {
+}
 
 finish_test

Index: src/vdbeInt.h
==================================================================
--- src/vdbeInt.h
+++ src/vdbeInt.h
@@ -428,12 +428,12 @@
   UnpackedRecord *pUnpacked;      /* Unpacked version of aRecord[] */
   UnpackedRecord *pNewUnpacked;   /* Unpacked version of new.* record */
   int iNewReg;                    /* Register for new.* values */
   i64 iKey1;                      /* First key value passed to hook */
   i64 iKey2;                      /* Second key value passed to hook */
-  int iPKey;                      /* If not negative index of IPK column */
   Mem *aNew;                      /* Array of new.* values */
+  Table *pTab;                    /* Schema object being upated */          
 };
 
 /*
 ** Function prototypes
 */

Index: src/vdbeapi.c
==================================================================
--- src/vdbeapi.c
+++ src/vdbeapi.c
@@ -1708,13 +1708,18 @@
   }
 
   if( iIdx>=p->pUnpacked->nField ){
     *ppValue = (sqlite3_value *)columnNullValue();
   }else{
+    Mem *pMem = *ppValue = &p->pUnpacked->aMem[iIdx];
     *ppValue = &p->pUnpacked->aMem[iIdx];
-    if( iIdx==p->iPKey ){
-      sqlite3VdbeMemSetInt64(*ppValue, p->iKey1);
+    if( iIdx==p->pTab->iPKey ){
+      sqlite3VdbeMemSetInt64(pMem, p->iKey1);
+    }else if( p->pTab->aCol[iIdx].affinity==SQLITE_AFF_REAL ){
+      if( pMem->flags & MEM_Int ){
+        sqlite3VdbeMemRealify(pMem);
+      }
     }
   }
 
  preupdate_old_out:
   sqlite3Error(db, rc);
@@ -1787,11 +1792,11 @@
     }
     if( iIdx>=pUnpack->nField ){
       pMem = (sqlite3_value *)columnNullValue();
     }else{
       pMem = &pUnpack->aMem[iIdx];
-      if( iIdx==p->iPKey ){
+      if( iIdx==p->pTab->iPKey ){
         sqlite3VdbeMemSetInt64(pMem, p->iKey2);
       }
     }
   }else{
     /* For an UPDATE, memory cell (p->iNewReg+1+iIdx) contains the required
@@ -1808,11 +1813,11 @@
       }
     }
     assert( iIdx>=0 && iIdx<p->pCsr->nField );
     pMem = &p->aNew[iIdx];
     if( pMem->flags==0 ){
-      if( iIdx==p->iPKey ){
+      if( iIdx==p->pTab->iPKey ){
         sqlite3VdbeMemSetInt64(pMem, p->iKey2);
       }else{
         rc = sqlite3VdbeMemCopy(pMem, &p->v->aMem[p->iNewReg+1+iIdx]);
         if( rc!=SQLITE_OK ) goto preupdate_new_out;
       }

Index: src/vdbeaux.c
==================================================================
--- src/vdbeaux.c
+++ src/vdbeaux.c
@@ -4615,11 +4615,11 @@
   preupdate.keyinfo.enc = ENC(db);
   preupdate.keyinfo.nField = pTab->nCol;
   preupdate.keyinfo.aSortOrder = (u8*)&fakeSortOrder;
   preupdate.iKey1 = iKey1;
   preupdate.iKey2 = iKey2;
-  preupdate.iPKey = pTab->iPKey;
+  preupdate.pTab = pTab;
 
   db->pPreUpdate = &preupdate;
   db->xPreUpdateCallback(db->pPreUpdateArg, db, op, zDb, zTbl, iKey1, iKey2);
   db->pPreUpdate = 0;
   sqlite3DbFree(db, preupdate.aRecord);