public static ShowResultSet execute(ShowStmt statement, ConnectContext context) {
        return GlobalStateMgr.getCurrentState().getShowExecutor().showExecutorVisitor.visit(statement, context);
    }
@Test
    public void testShowMaterializedViewFromUnknownDatabase() throws DdlException, AnalysisException {
        ShowMaterializedViewsStmt stmt = new ShowMaterializedViewsStmt("emptyDb", (String) null);

        expectedEx.expect(SemanticException.class);
        expectedEx.expectMessage("Unknown database 'emptyDb'");
        ShowExecutor.execute(stmt, ctx);
    }