realization of an algorithm in SQL query - sql

Question

I have a database which has 2 tables:
CREATE TABLE RecipeDB (
RecipeID INT PRIMARY KEY AUTO_INCREMENT,
Name VARCHAR,
Recipe VARCHAR,
Origin VARCHAR,
Category VARCHAR,
Favoured BOOL);
CREATE TABLE IngredientDB (
RecipeID REFERENCES RecipeDB.RecipeID,
Ingredient VARCHAR,
Quantity VARCHAR);
(One-to-many relation between Recipe and Ingredients)
I also have an actionscript, in which I have ingArr:Array of ingredient strings.
Now, I would like to realize the following queries here:
1) Select (all fields) one recipe which has the most of ingredients from the array. If more than one record have the same amount of matches, then divide the number of matches by total number of ingredients in recipe and return the one with the highest ratio. If there are no matches return nothing.
2) As above, but return 10 recipes with the most matches and do not perform check for equal number of matches. Sort the results by the number of matches.
Any ideas how to compose those queries in SQLite?

Answer 1

(The SQL statement provide under are for SQLite)
So for the second one you need the top 10 recipee that match the most ingredient
What you need is:
count the row that match your ingredient list (use IN operator)
order the result by best count in descendant order (4,3,2,...)
limit the result by 10
So the sql statement looks like
SELECT
r.RecipeId, COUNT(1) cnt, r.Name, r.Recipe, r.Origin, r.Category, r.Favoured
FROM
RecipeDB r
INNER JOIN IngredientDB i USING(RecipeID)
WHERE
i.Ingredient in ('ingr_1',..,'ingr_x')
GROUP BY 1
ORDER BY 2 DESC
LIMIT 10
using AIR + AS3 it can be something like that :
var sqls:SQLStatement = new SQLStatement()
sqls.sqlConnection = YOUR SQL CONNECTION
// your ingredient list
var ingredients:Array = ['i2', 'i3', 'i4']
// use to build the in parameter array
var inParams:Array = []
// fill parameter values
for(var i:int = 0; i < ingredients.length; ++i) {
inParams[i] = '?'
sqls.parameters[i] = ingredients[i]
}
// build the query
var qry:String = "SELECT r.RecipeId, COUNT(1) cnt, r.Name, r.Recipe, r.Origin,"+
"r.Category, r.Favoured FROM RecipeDB r INNER JOIN IngredientDB i USING(RecipeID)"+
"WHERE i.Ingredient in (" + inParams.join(',') + ") GROUP BY 1 "+
"ORDER BY 2 DESC LIMIT 10"
// set the query
sqls.text = qry
//execute
sqls.execute()
And for the first one same idea as above but you need to count also all the ingredient present into the recipee to provide a ratio between match / total
What you need is:
count the row that match your ingredient list (use IN operator)
make a rank by divide previous count by all total ingredient
get the best match
limit the result by 1
So the sql statement looks like :
SELECT
i1.RecipeId, (cast(rs.cnt as real) / cast (COUNT(1) as real)) rank,
rs.Name, rs.Recipe, rs.Origin, rs.Category, rs.Favoured
FROM
IngredientDB i1
INNER JOIN (
SELECT
r.RecipeId, COUNT(1) cnt, r.Name, r.Recipe, r.Origin, r.Category, r.Favoured
FROM
RecipeDB r
INNER JOIN IngredientDB i USING(RecipeID)
WHERE
i.Ingredient in ('ingr_1',..,'ingr_x')
GROUP BY 1
) rs USING (RecipeId)
GROUP BY 1
ORDER BY 2 DESC
LIMIT 1
Using the same logic as for the first example your query can be written as :
var ingredients:Array = ['i2', 'i3', 'i4']
var inParams:Array = []
for(var i:int = 0; i < ingredients.length; ++i) {
inParams[i] = '?'
sqls.parameters[i] = ingredients[i]
}
var qry:String = "SELECT i1.RecipeId, (cast(rs.cnt as real) / cast (COUNT(1) as real)) rank,"+
"rs.Name, rs.Recipe, rs.Origin, rs.Category, rs.Favoured "+
"FROM IngredientDB i1 INNER JOIN ("+
"SELECT r.RecipeId, COUNT(1) cnt, r.Name, r.Recipe, r.Origin, r.Category, r.Favoured "+
"FROM RecipeDB r INNER JOIN IngredientDB i USING(RecipeID) "+
"WHERE i.Ingredient in (" + inParams.join(',') + ") GROUP BY 1) rs USING (RecipeId) "+
"GROUP BY 1 ORDER BY 2 DESC LIMIT 1"

Answer 2

The queries can be tuned slightly, but the T-SQL below demonstrates the answers your looking for in a fairly readable way.
BEGIN
-- setup test
DECLARE #one TABLE(id INT, name VARCHAR(10))
DECLARE #many TABLE(pid INT, name VARCHAR(10))
INSERT INTO #one VALUES
(1, 'AAA'),
(2, 'BBB'),
(3, 'CCC')
INSERT INTO #many VALUES
(1, 'x'),(1, 'y'),(1, 'z'),
(2, 'x'),(2, 'y'),
(3, 'z')
--
-- WHERE m.name IN ('x', 'y')
-- 'x', 'y' represent your list of ingrediants
-- answer 1
SELECT * FROM #one WHERE id = (
SELECT TOP 1 x.id FROM (
SELECT o.id, COUNT(o.id) 'match', (SELECT COUNT(*) FROM #many WHERE pid=o.id) 'total' FROM #one o
INNER JOIN #many m ON o.id = m.pid
WHERE m.name IN ('x', 'y', 'z')
GROUP BY o.id
) as x ORDER BY x.match DESC, x.match/x.total DESC
)
-- answer 2
SELECT * FROM #one WHERE id IN (
SELECT TOP 10 x.id FROM (
SELECT o.id, COUNT(o.id) 'match' FROM #one o
INNER JOIN #many m ON o.id = m.pid
WHERE m.name IN ('x', 'y')
GROUP BY o.id
) as x ORDER BY x.match DESC
)
END