pDb->zNull = 0;
      }
    }
    Tcl_SetObjResult(interp, dbTextToObj(pDb->zNull));
    break;
  }

  /*
  **     $db last_insert_rowid 
  **
  ** Return an integer which is the ROWID for the most recent insert.
  */
  case DB_LAST_INSERT_ROWID: {
    Tcl_Obj *pResult;
    Tcl_WideInt rowid;
    if( objc!=2 ){
      Tcl_WrongNumArgs(interp, 2, objv, "");
      return TCL_ERROR;
    }
    rowid = sqlite3_last_insert_rowid(pDb->db);
    pResult = Tcl_GetObjResult(interp);
    Tcl_SetWideIntObj(pResult, rowid);
    break;
  }

  /*
  ** The DB_ONECOLUMN method is implemented together with DB_EVAL.
  */

  /*    $db progress ?N CALLBACK?
  ** 
  ** Invoke the given callback every N virtual machine opcodes while executing
  ** queries.
  */
  case DB_PROGRESS: {
    if( objc==2 ){
      if( pDb->zProgress ){
        Tcl_AppendResult(interp, pDb->zProgress, 0);
      }
    }else if( objc==4 ){
      char *zProgress;
      int len;
      int N;
      if( TCL_OK!=Tcl_GetIntFromObj(interp, objv[2], &N) ){
	return TCL_ERROR;
      };
      if( pDb->zProgress ){
        Tcl_Free(pDb->zProgress);
      }
      zProgress = Tcl_GetStringFromObj(objv[3], &len);
      if( zProgress && len>0 ){
        pDb->zProgress = Tcl_Alloc( len + 1 );
        strcpy(pDb->zProgress, zProgress);
      }else{
        pDb->zProgress = 0;
      }
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
      if( pDb->zProgress ){
        pDb->interp = interp;
        sqlite3_progress_handler(pDb->db, N, DbProgressHandler, pDb);
      }else{
        sqlite3_progress_handler(pDb->db, 0, 0, 0);
      }
#endif
    }else{
      Tcl_WrongNumArgs(interp, 2, objv, "N CALLBACK");
      return TCL_ERROR;
    }
    break;
  }

  /*    $db profile ?CALLBACK?
  **
  ** Make arrangements to invoke the CALLBACK routine after each SQL statement
  ** that has run.  The text of the SQL and the amount of elapse time are
  ** appended to CALLBACK before the script is run.
  */
  case DB_PROFILE: {
    if( objc>3 ){
      Tcl_WrongNumArgs(interp, 2, objv, "?CALLBACK?");
      return TCL_ERROR;
    }else if( objc==2 ){
      if( pDb->zProfile ){
        Tcl_AppendResult(interp, pDb->zProfile, 0);
      }
    }else{
      char *zProfile;
      int len;
      if( pDb->zProfile ){
        Tcl_Free(pDb->zProfile);
      }
      zProfile = Tcl_GetStringFromObj(objv[2], &len);
      if( zProfile && len>0 ){
        pDb->zProfile = Tcl_Alloc( len + 1 );
        strcpy(pDb->zProfile, zProfile);
      }else{
        pDb->zProfile = 0;
      }
#ifndef SQLITE_OMIT_TRACE
      if( pDb->zProfile ){
        pDb->interp = interp;
        sqlite3_profile(pDb->db, DbProfileHandler, pDb);
      }else{
        sqlite3_profile(pDb->db, 0, 0);
      }
#endif
    }
    break;
  }

  /*
  **     $db rekey KEY
  **
  ** Change the encryption key on the currently open database.
  */
  case DB_REKEY: {
    int nKey;
    void *pKey;
    if( objc!=3 ){
      Tcl_WrongNumArgs(interp, 2, objv, "KEY");
      return TCL_ERROR;
    }
    pKey = Tcl_GetByteArrayFromObj(objv[2], &nKey);
#ifdef SQLITE_HAS_CODEC
    rc = sqlite3_rekey(pDb->db, pKey, nKey);
    if( rc ){
      Tcl_AppendResult(interp, sqlite3ErrStr(rc), 0);
      rc = TCL_ERROR;
    }
#endif
    break;
  }

  /*
  **     $db timeout MILLESECONDS
  **
  ** Delay for the number of milliseconds specified when a file is locked.
  */
  case DB_TIMEOUT: {
    int ms;
    if( objc!=3 ){
      Tcl_WrongNumArgs(interp, 2, objv, "MILLISECONDS");
      return TCL_ERROR;
    }
    if( Tcl_GetIntFromObj(interp, objv[2], &ms) ) return TCL_ERROR;
    sqlite3_busy_timeout(pDb->db, ms);
    break;
  }
  
  /*
  **     $db total_changes
  **
  ** Return the number of rows that were modified, inserted, or deleted 
  ** since the database handle was created.
  */
  case DB_TOTAL_CHANGES: {
    Tcl_Obj *pResult;
    if( objc!=2 ){
      Tcl_WrongNumArgs(interp, 2, objv, "");
      return TCL_ERROR;
    }
    pResult = Tcl_GetObjResult(interp);
    Tcl_SetIntObj(pResult, sqlite3_total_changes(pDb->db));
    break;
  }

  /*    $db trace ?CALLBACK?
  **
  ** Make arrangements to invoke the CALLBACK routine for each SQL statement
  ** that is executed.  The text of the SQL is appended to CALLBACK before
  ** it is executed.
  */
  case DB_TRACE: {
    if( objc>3 ){
      Tcl_WrongNumArgs(interp, 2, objv, "?CALLBACK?");
      return TCL_ERROR;
    }else if( objc==2 ){
      if( pDb->zTrace ){
        Tcl_AppendResult(interp, pDb->zTrace, 0);
      }
    }else{
      char *zTrace;
      int len;
      if( pDb->zTrace ){
        Tcl_Free(pDb->zTrace);
      }
      zTrace = Tcl_GetStringFromObj(objv[2], &len);
      if( zTrace && len>0 ){
        pDb->zTrace = Tcl_Alloc( len + 1 );
        strcpy(pDb->zTrace, zTrace);
      }else{
        pDb->zTrace = 0;
      }
#ifndef SQLITE_OMIT_TRACE
      if( pDb->zTrace ){
        pDb->interp = interp;
        sqlite3_trace(pDb->db, DbTraceHandler, pDb);
      }else{
        sqlite3_trace(pDb->db, 0, 0);
      }
#endif
    }
    break;
  }

  /*    $db transaction [-deferred|-immediate|-exclusive] SCRIPT
  **
  ** Start a new transaction (if we are not already in the midst of a
  ** transaction) and execute the TCL script SCRIPT.  After SCRIPT
  ** completes, either commit the transaction or roll it back if SCRIPT
  ** throws an exception.  Or if no new transation was started, do nothing.
  ** pass the exception on up the stack.
  **
  ** This command was inspired by Dave Thomas's talk on Ruby at the
  ** 2005 O'Reilly Open Source Convention (OSCON).
  */
  case DB_TRANSACTION: {
    int inTrans;
    Tcl_Obj *pScript;
    const char *zBegin = "BEGIN";
    if( objc!=3 && objc!=4 ){
      Tcl_WrongNumArgs(interp, 2, objv, "[TYPE] SCRIPT");
      return TCL_ERROR;
    }
    if( objc==3 ){
      pScript = objv[2];
    } else {
      static const char *TTYPE_strs[] = {
        "deferred",   "exclusive",  "immediate", 0
      };
      enum TTYPE_enum {
        TTYPE_DEFERRED, TTYPE_EXCLUSIVE, TTYPE_IMMEDIATE
      };
      int ttype;
      if( Tcl_GetIndexFromObj(interp, objv[2], TTYPE_strs, "transaction type",
                              0, &ttype) ){
        return TCL_ERROR;
      }
      switch( (enum TTYPE_enum)ttype ){
        case TTYPE_DEFERRED:    /* no-op */;                 break;
        case TTYPE_EXCLUSIVE:   zBegin = "BEGIN EXCLUSIVE";  break;
        case TTYPE_IMMEDIATE:   zBegin = "BEGIN IMMEDIATE";  break;
      }
      pScript = objv[3];
    }
    inTrans = !sqlite3_get_autocommit(pDb->db);
    if( !inTrans ){
      (void)sqlite3_exec(pDb->db, zBegin, 0, 0, 0);
    }
    rc = Tcl_EvalObjEx(interp, pScript, 0);
    if( !inTrans ){
      const char *zEnd;
      if( rc==TCL_ERROR ){
        zEnd = "ROLLBACK";
      } else {
        zEnd = "COMMIT";
      }
      (void)sqlite3_exec(pDb->db, zEnd, 0, 0, 0);
    }
    break;
  }

  /*
  **    $db update_hook ?script?
  **    $db rollback_hook ?script?
  */
  case DB_UPDATE_HOOK: 
  case DB_ROLLBACK_HOOK: {

    /* set ppHook to point at pUpdateHook or pRollbackHook, depending on 
    ** whether [$db update_hook] or [$db rollback_hook] was invoked.
    */
    Tcl_Obj **ppHook; 
    if( choice==DB_UPDATE_HOOK ){
      ppHook = &pDb->pUpdateHook;
    }else{
      ppHook = &pDb->pRollbackHook;
    }

    if( objc!=2 && objc!=3 ){
       Tcl_WrongNumArgs(interp, 2, objv, "?SCRIPT?");
       return TCL_ERROR;
    }
    if( *ppHook ){
      Tcl_SetObjResult(interp, *ppHook);
      if( objc==3 ){
        Tcl_DecrRefCount(*ppHook);
        *ppHook = 0;
      }
    }
    if( objc==3 ){
      assert( !(*ppHook) );
      if( Tcl_GetCharLength(objv[2])>0 ){
        *ppHook = objv[2];
        Tcl_IncrRefCount(*ppHook);
      }
    }

    sqlite3_update_hook(pDb->db, (pDb->pUpdateHook?DbUpdateHandler:0), pDb);
    sqlite3_rollback_hook(pDb->db,(pDb->pRollbackHook?DbRollbackHandler:0),pDb);

    break;
  }

  /*    $db version
  **
  ** Return the version string for this database.
  */
  case DB_VERSION: {
    Tcl_SetResult(interp, (char *)sqlite3_libversion(), TCL_STATIC);
    break;
  }


  } /* End of the SWITCH statement */
  return rc;
}

/*
**   sqlite3 DBNAME FILENAME ?MODE? ?-key KEY?
**
** This is the main Tcl command.  When the "sqlite" Tcl command is
** invoked, this routine runs to process that command.
**
** The first argument, DBNAME, is an arbitrary name for a new
** database connection.  This command creates a new command named
** DBNAME that is used to control that connection.  The database
** connection is deleted when the DBNAME command is deleted.
**
** The second argument is the name of the directory that contains
** the sqlite database that is to be accessed.
**
** For testing purposes, we also support the following:
**
**  sqlite3 -encoding
**
**       Return the encoding used by LIKE and GLOB operators.  Choices
**       are UTF-8 and iso8859.
**
**  sqlite3 -version
**
**       Return the version number of the SQLite library.
**
**  sqlite3 -tcl-uses-utf
**
**       Return "1" if compiled with a Tcl uses UTF-8.  Return "0" if
**       not.  Used by tests to make sure the library was compiled 
**       correctly.
*/
static int DbMain(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
  SqliteDb *p;
  void *pKey = 0;
  int nKey = 0;
  const char *zArg;
  char *zErrMsg;
  const char *zFile;
  Tcl_DString translatedFilename;
  if( objc==2 ){
    zArg = Tcl_GetStringFromObj(objv[1], 0);
    if( strcmp(zArg,"-version")==0 ){
      Tcl_AppendResult(interp,sqlite3_version,0);
      return TCL_OK;
    }
    if( strcmp(zArg,"-has-codec")==0 ){
#ifdef SQLITE_HAS_CODEC
      Tcl_AppendResult(interp,"1",0);
#else
      Tcl_AppendResult(interp,"0",0);
#endif
      return TCL_OK;
    }
    if( strcmp(zArg,"-tcl-uses-utf")==0 ){
#ifdef TCL_UTF_MAX
      Tcl_AppendResult(interp,"1",0);
#else
      Tcl_AppendResult(interp,"0",0);
#endif
      return TCL_OK;
    }
  }
  if( objc==5 || objc==6 ){
    zArg = Tcl_GetStringFromObj(objv[objc-2], 0);
    if( strcmp(zArg,"-key")==0 ){
      pKey = Tcl_GetByteArrayFromObj(objv[objc-1], &nKey);
      objc -= 2;
    }
  }
  if( objc!=3 && objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, 
#ifdef SQLITE_HAS_CODEC
      "HANDLE FILENAME ?-key CODEC-KEY?"
#else
      "HANDLE FILENAME ?MODE?"
#endif
    );
    return TCL_ERROR;
  }
  zErrMsg = 0;
  p = (SqliteDb*)Tcl_Alloc( sizeof(*p) );
  if( p==0 ){
    Tcl_SetResult(interp, "malloc failed", TCL_STATIC);
    return TCL_ERROR;
  }
  memset(p, 0, sizeof(*p));
  zFile = Tcl_GetStringFromObj(objv[2], 0);
  zFile = Tcl_TranslateFileName(interp, zFile, &translatedFilename);
  sqlite3_open(zFile, &p->db);
  Tcl_DStringFree(&translatedFilename);
  if( SQLITE_OK!=sqlite3_errcode(p->db) ){