liquibase-core/src/main/java/liquibase/changelog/StandardChangeLogHistoryService.java
@Override
    public void tag(final String tagString) throws DatabaseException {
        Database database = getDatabase();
        Executor executor = ExecutorService.getInstance().getExecutor(database);
        int totalRows = ExecutorService.getInstance().getExecutor(database).queryForInt(new
            SelectFromDatabaseChangeLogStatement(new ColumnConfig().setName("COUNT(*)", true)));
        if (totalRows == 0) {
            ChangeSet emptyChangeSet = new ChangeSet(String.valueOf(new Date().getTime()), "liquibase",
                false,false, "liquibase-internal", null, null,
                getDatabase().getObjectQuotingStrategy(), null);
            this.setExecType(emptyChangeSet, ChangeSet.ExecType.EXECUTED);
        }

        executor.execute(new TagDatabaseStatement(tagString));
        getDatabase().commit();

        if (this.ranChangeSetList != null) {
            ranChangeSetList.get(ranChangeSetList.size() - 1).setTag(tagString);
        }
    }
@Override
    public void tag(final String tagString) throws DatabaseException {
        Database database = getDatabase();
        Executor executor = ExecutorService.getInstance().getExecutor(database);
        int totalRows = ExecutorService.getInstance().getExecutor(database).queryForInt(new
            SelectFromDatabaseChangeLogStatement(new ColumnConfig().setName("COUNT(*)", true)));
        if (totalRows == 0) {
            ChangeSet emptyChangeSet = new ChangeSet(String.valueOf(new Date().getTime()), "liquibase",
                false,false, "liquibase-internal", null, null,
                getDatabase().getObjectQuotingStrategy(), null);
            this.setExecType(emptyChangeSet, ChangeSet.ExecType.EXECUTED);
        }

        executor.execute(new TagDatabaseStatement(tagString));
        getDatabase().commit();

        if (this.ranChangeSetList != null) {
            ranChangeSetList.get(ranChangeSetList.size() - 1).setTag(tagString);
        }
    }
Tags the database changelog with the given string.