Index: src/pragma.h
==================================================================
--- src/pragma.h
+++ src/pragma.h
@@ -438,10 +438,19 @@
   /* ePragFlg:  */ PragFlg_Result0,
   /* ColNames:  */ 31, 1,
   /* iArg:      */ 0 },
 #endif
 #endif
+#endif
+#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+#if defined(SQLITE_DEBUG)
+ {/* zName:     */ "noop_update",
+  /* ePragTyp:  */ PragTyp_FLAG,
+  /* ePragFlg:  */ PragFlg_Result0|PragFlg_NoColumns1,
+  /* ColNames:  */ 0, 0,
+  /* iArg:      */ SQLITE_NoopUpdate },
+#endif
 #endif
  {/* zName:     */ "optimize",
   /* ePragTyp:  */ PragTyp_OPTIMIZE,
   /* ePragFlg:  */ PragFlg_Result1|PragFlg_NeedSchema,
   /* ColNames:  */ 0, 0,
@@ -644,6 +653,6 @@
   /* ePragFlg:  */ PragFlg_Result0|PragFlg_NoColumns1,
   /* ColNames:  */ 0, 0,
   /* iArg:      */ SQLITE_WriteSchema },
 #endif
 };
-/* Number of pragmas: 60 on by default, 77 total. */
+/* Number of pragmas: 60 on by default, 78 total. */

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -1489,10 +1489,11 @@
 #define SQLITE_CellSizeCk     0x00200000  /* Check btree cell sizes on load */
 #define SQLITE_Fts3Tokenizer  0x00400000  /* Enable fts3_tokenizer(2) */
 #define SQLITE_EnableQPSG     0x00800000  /* Query Planner Stability Guarantee */
 /* Flags used only if debugging */
 #ifdef SQLITE_DEBUG
+#define SQLITE_NoopUpdate     0x04000000  /* UPDATE operations are no-ops */
 #define SQLITE_SqlTrace       0x08000000  /* Debug print SQL as it executes */
 #define SQLITE_VdbeListing    0x10000000  /* Debug listings of VDBE programs */
 #define SQLITE_VdbeTrace      0x20000000  /* True to trace VDBE execution */
 #define SQLITE_VdbeAddopTrace 0x40000000  /* Trace sqlite3VdbeAddOp() calls */
 #define SQLITE_VdbeEQP        0x80000000  /* Debug EXPLAIN QUERY PLAN */

Index: src/update.c
==================================================================
--- src/update.c
+++ src/update.c
@@ -221,10 +221,21 @@
   ** column to be updated, make sure we have authorization to change
   ** that column.
   */
   chngRowid = chngPk = 0;
   for(i=0; i<pChanges->nExpr; i++){
+#if defined(SQLITE_DEBUG) && !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+    if( db->flags & SQLITE_NoopUpdate ){
+      Token x;
+      sqlite3ExprDelete(db, pChanges->a[i].pExpr);
+      x.z = pChanges->a[i].zName;
+      x.n = sqlite3Strlen30(x.z);
+      pChanges->a[i].pExpr =
+         sqlite3PExpr(pParse, TK_UPLUS, sqlite3ExprAlloc(db, TK_ID, &x, 0), 0);
+      if( db->mallocFailed ) goto update_cleanup;
+    }
+#endif
     if( sqlite3ResolveExprNames(&sNC, pChanges->a[i].pExpr) ){
       goto update_cleanup;
     }
     for(j=0; j<pTab->nCol; j++){
       if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){

Index: tool/mkpragmatab.tcl
==================================================================
--- tool/mkpragmatab.tcl
+++ tool/mkpragmatab.tcl
@@ -107,10 +107,16 @@
   IF:   defined(SQLITE_DEBUG)
 
   NAME: vdbe_eqp
   TYPE: FLAG
   ARG:  SQLITE_VdbeEQP
+  IF:   !defined(SQLITE_OMIT_FLAG_PRAGMAS)
+  IF:   defined(SQLITE_DEBUG)
+
+  NAME: noop_update
+  TYPE: FLAG
+  ARG:  SQLITE_NoopUpdate
   IF:   !defined(SQLITE_OMIT_FLAG_PRAGMAS)
   IF:   defined(SQLITE_DEBUG)
 
   NAME: ignore_check_constraints
   TYPE: FLAG