private boolean validateColumnsRecurse(TExpression condition, TJoinList joins) { if (condition.getLeftOperand().getLeftOperand() == null && condition.getRightOperand().getLeftOperand() == null) { return validateColumns(condition.getLeftOperand().toString(), joins) .equals(validateColumns(condition.getRightOperand().toString(), joins)); } else { return (validateColumnsRecurse(condition.getLeftOperand(), joins) && validateColumnsRecurse(condition.getRightOperand(), joins)); } }