Index: src/pragma.c
==================================================================
--- src/pragma.c
+++ src/pragma.c
@@ -175,10 +175,11 @@
     { "empty_result_callbacks",   SQLITE_NullCallback  },
     { "legacy_file_format",       SQLITE_LegacyFileFmt },
     { "fullfsync",                SQLITE_FullFSync     },
     { "checkpoint_fullfsync",     SQLITE_CkptFullFSync },
     { "reverse_unordered_selects", SQLITE_ReverseOrder  },
+    { "query_only",               SQLITE_QueryOnly     },
 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
     { "automatic_index",          SQLITE_AutoIndex     },
 #endif
 #ifdef SQLITE_DEBUG
     { "sql_trace",                SQLITE_SqlTrace      },

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -1007,10 +1007,11 @@
 #define SQLITE_ForeignKeys    0x00040000  /* Enforce foreign key constraints  */
 #define SQLITE_AutoIndex      0x00080000  /* Enable automatic indexes */
 #define SQLITE_PreferBuiltin  0x00100000  /* Preference to built-in funcs */
 #define SQLITE_LoadExtension  0x00200000  /* Enable load_extension */
 #define SQLITE_EnableTrigger  0x00400000  /* True to enable triggers */
+#define SQLITE_QueryOnly      0x00800000  /* Disable database changes */
 
 /*
 ** Bits of the sqlite3.dbOptFlags field that are used by the
 ** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface to
 ** selectively disable various optimizations.

Index: src/vdbe.c
==================================================================
--- src/vdbe.c
+++ src/vdbe.c
@@ -2944,10 +2944,14 @@
 
   assert( p->bIsReader );
   assert( p->readOnly==0 || pOp->p2==0 );
   assert( pOp->p1>=0 && pOp->p1<db->nDb );
   assert( (p->btreeMask & (((yDbMask)1)<<pOp->p1))!=0 );
+  if( pOp->p2 && (db->flags & SQLITE_QueryOnly)!=0 ){
+    rc = SQLITE_READONLY;
+    goto abort_due_to_error;
+  }
   pBt = db->aDb[pOp->p1].pBt;
 
   if( pBt ){
     rc = sqlite3BtreeBeginTrans(pBt, pOp->p2);
     if( rc==SQLITE_BUSY ){