MySQL group duplicate ID without loosing other data - mysql

Question

I'm trying to make a cookbook and I'm having an issue with duplication. It will be easier to understand with an example, so let's begin:
My tables look like this:
create table Recipe (
id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(25),
description VARCHAR(50),
instructions VARCHAR(500))
ENGINE=InnoDB DEFAULT CHARSET=utf8;
create table Ingredient (
id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(50))
ENGINE=InnoDB DEFAULT CHARSET=utf8;
create table Measure (
id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(30))
ENGINE=InnoDB DEFAULT CHARSET=utf8;
create table RecipeIngredient (
recipe_id INT NOT NULL,
ingredient_id INT NOT NULL,
measure_id INT,
amount INT,
CONSTRAINT fk_recipe FOREIGN KEY(recipe_id) REFERENCES Recipe(id),
CONSTRAINT fk_ingredient FOREIGN KEY(ingredient_id) REFERENCES Ingredient(id),
CONSTRAINT fk_measure FOREIGN KEY(measure_id) REFERENCES Measure(id))
ENGINE=InnoDB DEFAULT CHARSET=utf8;
and when I run a query that looks like this:
SELECT r.name AS 'Recipe',
r.instructions,
ri.amount AS 'Amount',
mu.name AS 'Unit of Measure',
i.name AS 'Ingredient'
FROM Recipe r
JOIN RecipeIngredient ri on r.id = ri.recipe_id
JOIN Ingredient i on i.id = ri.ingredient_id
LEFT OUTER JOIN Measure mu on mu.id = measure_id;
I'm getting this result :
The problem is that Chocolate Cake is duplicating even though it's the same recipe it just has more than one ingredient. Could you please help me solve this problem, so I would get one instance of Recipe?

Answer 1

Use GROUP_CONCAT to combine values from multiple rows in a group into a comma-separated list. And use CONCAT to concatenate strings, like concatenating the amount to the unit and ingredient.
SELECT r.name, r.instructions,
GROUP_CONCAT(CONCAT(ri.amount, mu.name, ' ', i.name)) AS ingredients
FROM Recipe r
JOIN RecipeIngredient ri on r.id = ri.recipe_id
JOIN Ingredient i on i.id = ri.ingredient_id
LEFT OUTER JOIN Measure mu on mu.id = measure_id
GROUP BY r.id;