}
if (this.pattern != null) {
return new Pattern(this.pattern);
}
if (this.sqlExpression != null) {
return new SQLExpressionValueMaker(SQLExpression.create(sqlExpression));
}
if (this.uriSqlExpression != null) {
return new SQLExpressionValueMaker(SQLExpression.create(uriSqlExpression));
}
throw new D2RQException(this + " needs a column/pattern/bNodeID specification");
}