Creating a scoring column based on threatened species lists

Question

I'm doing scoring for sites based on the number of threatened species at each particular site and the threat status of each of the threatened species.
A threatened species could either have a threat status of nationally_critical, nationally_endangered, or nationally_vulnerable.
I am trying to write a query will display a column called TOTAL_SCORE where:
TOTAL_SCORE = (number of Nationally Critical species * 1) + (number of Nationally Endangered species * 0.5) + (number of Nationally Vulnerable species * 0.25)
I'm able to do this using excel formulas but I have no idea how to go about writing it in SQL. I would have attached the excel spreadsheet but attachments are not allowed in this forum I think?
See below for descriptions and DDL for the tables I have:
I have three tables: SITES, SPECIES_LIST, THREAT_STATUS_SCORES
The SITES table contains the site number and the species present at each particular site:
SITE_NUMBER    SPECIES_PRESENT
1            Olearia_pachyphylla, Oligosoma_whitakeri, Spio_aequalis
2            Ophioglossum_petiolatum, Ourisia_modesta, Pachycladon_exile
3            Dichelachne_micrantha, Galaxias_pullus
4            Spio_aequalis
5            Pachycladon_exile, Geranium_retrorsum
6            Olearia_pachyphylla, Ourisia_modesta, Oligosoma_judgei
7            Drosera_pygmaeaThe SPECIES_LIST table has a list of nationally critical, nationally endangered, and nationally vulnerable species:
NATIONALLY_CRITICAL               NATIONALLY_ENDANGERED      NATIONALLY_VULNERABLE
Olearia_pachyphylla               Oligosoma_judgei          Dichelachne_micrantha
Ophioglossum_petiolatum               Oligosoma_whitakeri          Drosera_pygmaea
Ourisia_modesta                       Spio_aequalis                  Geranium_retrorsum
Pachycladon_exile               Galaxias_pullus          Gratiola_concinnaThe THREAT_STATUS_SCORES table shows the score given to each threat status i.e. each nationally vulnerable species gets a score of 1,
each nationally endangered species gets a score of 0.5, and each nationally vulnerable gets a score of 0.25:
THREAT_STATUS           SCORE
NATIONALLY_CRITICAL     1
NATIONALLY_ENDANGERED     0.5
NATIONALLY_VULNERABLE     0.25DDL:
CREATE TABLE sites
(site_number varchar2(3) not null,
species_present varchar2(255),
CONSTRAINT site_number_pk PRIMARY KEY (site_number))
CREATE TABLE species_list
(nationally_critical varchar2(50),
nationally_endangered varchar2(50),
nationally_vulnerable varchar2(50))
CREATE TABLE threat_status_scores
(threat_status varchar2(50),
score number(4,2))
INSERT INTO sites VALUES (1, Olearia_pachyphylla, Oligosoma_whitakeri, Spio_aequalis);
INSERT INTO sites VALUES (2, Ophioglossum_petiolatum, Ourisia_modesta, Pachycladon_exile);
INSERT INTO sites VALUES (3, Dichelachne_micrantha, Galaxias_pullus);
INSERT INTO sites VALUES (4, Spio_aequalis);
INSERT INTO sites VALUES (5, Pachycladon_exile, Geranium_retrorsum);
INSERT INTO sites VALUES (6, Olearia_pachyphylla, Ourisia_modesta, Oligosoma_judgei);
INSERT INTO sites VALUES (7, Drosera_pygmaea);
INSERT INTO species_list VALUES (Olearia_pachyphylla, Oligosoma_judgei, Dichelachne_micrantha);
INSERT INTO species_list VALUES (Ophioglossum_petiolatum, Oligosoma_whitakeri, Drosera_pygmaea);
INSERT INTO species_list VALUES (Ourisia_modesta, Spio_aequalis, Geranium_retrorsum);
INSERT INTO species_list VALUES (Pachycladon_exile, Galaxias_pullus, Gratiola_concinna);
INSERT INTO threat_status_scores VALUES (NATIONALLY_CRITICAL, 1);
INSERT INTO threat_status_scores VALUES (NATIONALLY_ENDANGERED, 0.5);
INSERT INTO threat_status_scores VALUES (NATIONALLY_VULNERABLE, 0.25);Any help on how I could add a TOTAL_SCORE column to the SITES table would be much appreciated.
I'm using oracle 11g
Edited by: 993451 on Apr 1, 2013 4:01 PM
Edited by: 993451 on Apr 1, 2013 4:02 PM

Answer 1

If you're using Oracle 11.2, then the query for total_scores might be:
SELECT    pr.site_number
,       LISTAGG (s.species_name, ', ') WITHIN GROUP (ORDER BY s.species_name)
                           AS species_present
,       SUM (t.score)          AS total_score
FROM       species_present     sp
JOIN       species          s   ON   s.species_id    = sp.secies_id
JOIN       threat_status_scores     t   ON   t.threat_level  = s.threat_level
GROUP BY  pr.site_number
ORDER BY  pr.site_numberThanks for this. This works great, all I needed to do was change a minor spelling error and not include the pr prefix at the start of site_number. What is the pr prefix? Sorry, I'm a beginner at sql.
Here is the new full DDL based on your post:
CREATE TABLE  species
(   species_id          NUMBER (10)     PRIMARY KEY
,   species_name     VARCHAR2 (50)     UNIQUE
,   threat_level     VARCHAR2 (1)     CONSTRAINT  species_danger_chk
                          CHECK  (threat_level IN ( 'C'
                                  , 'E'
                                  , 'V'
INSERT INTO species (species_id, species_name,          threat_level)
             VALUES (1,          'Olearia pachyphylla', 'C');
INSERT INTO species (species_id, species_name,          threat_level)
             VALUES (2,          'Oligosoma judgei',     'E');
INSERT INTO species (species_id, species_name,          threat_level)
             VALUES (3,          'Aster alpinus',     NULL);
CREATE TABLE species_present
(   site_number          NUMBER (10)
,   species_id          NUMBER (10)
,   CONSTRAINT species_present_pk PRIMARY KEY ( site_number
                                            , species_id
INSERT INTO species_present (site_number, species_id) VALUES (1, 1);
INSERT INTO species_present (site_number, species_id) VALUES (1, 4);
INSERT INTO species_present (site_number, species_id) VALUES (1, 9);
INSERT INTO species_present (site_number, species_id) VALUES (4, 9);
CREATE TABLE threat_status_scores
(threat_level varchar2(50),
score number(4,2));
INSERT INTO threat_status_scores VALUES ('C', 1);
INSERT INTO threat_status_scores VALUES ('E', 0.5);
INSERT INTO threat_status_scores VALUES ('V', 0.25);
SELECT    site_number
,       LISTAGG (s.species_name, ', ') WITHIN GROUP (ORDER BY s.species_name)
                           AS species_present
,       SUM (t.score)          AS total_score
FROM       species_present     sp
JOIN       species          s   ON   s.species_id    = sp.species_id
JOIN       threat_status_scores     t   ON   t.threat_level  = s.threat_level
GROUP BY  site_number
ORDER BY  site_number;>
Why not have one table, but a separate row for each species, with the level of endangerment (if any) being an attribiute of the species? The distinction between >citically endagered species and vulnerable species is important, of course, but aren't the two kinds iof species fundamentally the same kind of entity? Don't they >have the same kinds of attributes? Aren't they used in the same way?
Here's one possible table design:
You're right. It is much better to have a single table for threatened species with three columns: species_id, species_name, and threat_level.
Since species_name is unique, and (I imagine) it is unlikely to change, then there might be an argument for not having a species_id, and making species_name the >primary key.Species_names are unique, however believe it or not they do sometimes change - at least in New Zealand! The botanists and ecologists put out updated species lists every few years and occassionally they will change species names for various reasons.
You're right; that would be a problem. The number of columns in a table is fixed, and while that number can be adjusted, it's not something that people do all the >time. Tables can have as many rows as necessary, and adding or removing rows is easy. Put each sighting on a separate row, something like this:
CREATE TABLE species_present
(   site_number          NUMBER (10)
,   species_id          NUMBER (10)
,   CONSTRAINT species_present_pk PRIMARY KEY ( site_number
                                            , species_id
INSERT INTO species_present (site_number, species_id) VALUES (1, 1);
INSERT INTO species_present (site_number, species_id) VALUES (1, 4);
INSERT INTO species_present (site_number, species_id) VALUES (1, 9);
INSERT INTO species_present (site_number, species_id) VALUES (4, 9);I think that this is a good idea. However, I'm not allowed to change sites table (I should have mentioned this earlier).
What happens is that contractors collect the threatened species information and they have already put the table in this format:
CREATE TABLE sites
(site_number varchar2(3) not null,
species_present varchar2(255),
CONSTRAINT site_number_pk PRIMARY KEY (site_number))
INSERT INTO sites VALUES (1, 'Olearia_pachyphylla, Oligosoma_whitakeri, Spio_aequalis');
INSERT INTO sites VALUES (2, 'Ophioglossum_petiolatum, Ourisia_modesta, Pachycladon_exile');
INSERT INTO sites VALUES (3, 'Dichelachne_micrantha, Galaxias_pullus');
INSERT INTO sites VALUES (4, 'Spio_aequalis');
INSERT INTO sites VALUES (5, 'Pachycladon_exile, Geranium_retrorsum');
INSERT INTO sites VALUES (6, 'Olearia_pachyphylla, Ourisia_modesta, Oligosoma_judgei');
INSERT INTO sites VALUES (7, 'Drosera_pygmaea');