Classification table design skills for the food shopping system in MySQL
Introduction:
In the process of purchasing food, classification is very important. For a grocery shopping system, the design of the classification table is a very critical step. This article will introduce the techniques of designing the classification table of the grocery shopping system in MySQL and provide specific code examples.
1. Analyze requirements
Before designing the classification table, we need to analyze the requirements and determine the hierarchical structure and attributes of the classification. For a food shopping system, categories that can be considered include: ingredients, dishes, kitchen utensils, etc. These categories can be further subdivided. For example, ingredients can be divided into vegetables, fruits, meat, etc. On this basis, we can determine the fields of the classification table, such as classification ID, classification name, parent classification ID, etc.
2. Design category table
CREATE TABLE category (
category_id
INT(11) NOT NULL AUTO_INCREMENT,
category_name
VARCHAR (50) NOT NULL,
parent_id
INT(11) DEFAULT NULL,
PRIMARY KEY (category_id
),
INDEX idx_parent_id
( parent_id
),
FOREIGN KEY (parent_id
) REFERENCES category
(category_id
)
);
Description:
3. Insert categorical data
INSERT INTO category (category_name, parent_id) VALUES ('ingredients', NULL);
INSERT INTO category (category_name, parent_id) VALUES ( 'Vegetables', 1);
INSERT INTO category (category_name, parent_id) VALUES ('Fruit', 1);
INSERT INTO category (category_name, parent_id) VALUES ('Meat', 1);
INSERT INTO category (category_name, parent_id) VALUES ('dishes', NULL);
INSERT INTO category (category_name, parent_id) VALUES ('Sichuan cuisine', 5);
INSERT INTO category (category_name, parent_id) VALUES ('Cantonese Cuisine', 5);
INSERT INTO category (category_name, parent_id) VALUES ('Hunan Cuisine', 5);
INSERT INTO category (category_name, parent_id) VALUES ('Kitchen Utensils', NULL);
INSERT INTO category (category_name, parent_id) VALUES ('knives', 9);
INSERT INTO category (category_name, parent_id) VALUES ('cookware', 9);
INSERT INTO category (category_name, parent_id) VALUES ('Tableware', 9);
Note:
4. Query category data
SELECT p.category_name AS parent_category , c.category_name AS child_category
FROM category p
LEFT JOIN category c ON p.category_id = c.parent_id
WHERE p.parent_id IS NULL;
SELECT category_name FROM category WHERE parent_id = 1;
SELECT p .category_name AS parent_category, c.category_name AS child_category
FROM category p
JOIN category c ON p.category_id = c.parent_id
WHERE c.category_name = 'vegetable';
5. Summary
Through the above design and sample code, we can implement a grocery shopping system with classification function. Through the design of classification tables, we can flexibly manage and organize different ingredients, dishes, kitchen utensils, etc. I hope this article can provide you with some reference and help in designing classification tables in MySQL.
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