What is the best method to compare data using the join? - mysql

Question

I'm doing a section on my website called "My Ideal Surfboard", the user enters their data (weight, height, etc.), a comparison is made in database (join) and is returned to the ideal types of surfboard user according to his profile.
I have a table with the reference of all sizes and types of surfboard according to height, weight and user experience.
I'm doing the following:
Divided into two tables:
  - Table USER obviously stores user data (experience, height and weight);
  - Table SURFBOARD possesses the reference values (type, size, weight and litres) on each surfboardd according to experience, weight, height of the user.
-> I liken the table USER to the table SURFBOARD and return to the user the ideal model. How to do this?
At first I thought putting the same fields both in the table USER as in the table SURFBOARD make a inner join and have the data you want.
However, the both tables would duplicate values.
`dados_usuario` `prancha`
height2 weight2
height2 weight2
height2 weight2
height1 weight2
height1 weight2
height1 weight2
I compare and I display...
I believe that this is not a good practice and not the best way to do this. I know there are other methods to do this.
The issue is, how best way to compare these data?
How to identify which line is compatible with the data that the user will enter?
MY DATABASE:
CREATE TABLE USER(
usuario INT NOT NULL AUTO_INCREMENT,
nome VARCHAR(150) not null,
email VARCHAR(50) not null,
estilo VARCHAR(14) not null,
exp VARCHAR(13) not null,
altura VARCHAR(12) not null,
peso VARCHAR(9) not null,
PRIMARY KEY(usuario)
);
CREATE TABLE SUFBOARD(
prancha_pri INT NOT NULL AUTO_INCREMENT,
tipo_prancha VARCHAR(9) NOT NULL,
tamanho_prancha VARCHAR(9) not null,
meio_prancha VARCHAR(12) not null,
litragem_prancha VARCHAR(8) not null,
PRIMARY KEY (prancha_pri)
);
INSERTING DATA IN TABLE 'USER':
INSERT INTO EXPERIENCIA VALUES (NULL, 'joao', 'a#a.com', 'Surf', 'INICIANTE', '<1,60m', '>90kg');
INSERT INTO EXPERIENCIA VALUES (NULL, 'john', 'b#b.com', 'StandUP Paddle', 'INTERMEDIARIO', '1,81 - 1,90m', '81 - 90kg');
INSERT INTO EXPERIENCIA VALUES (NULL, 'carl', 'c#c.com', 'Surf', 'AVANÇADO', '>1,90m', '71 - 80kg');
INSERTING DATA IN TABLE SURFBOARD:
INSERT INTO PRANCHA VALUES (1, 'FUN', '8', '21 polegadas', '43L');
INSERT INTO PRANCHA VALUES (2, 'FUN', '8.8', '21 polegadas', '43L');
INSERT INTO PRANCHA VALUES (3, 'LONGBOARD', '9.2', '21 polegadas', '55L');
INSERT INTO PRANCHA VALUES (4, 'PRANCHA', '5.5 a 5.8', '20 polegadas', '30L');
INSERT INTO PRANCHA VALUES (5, 'PRANCHA', '5.5 a 5.10', '20 polegadas', '30L');
INSERT INTO PRANCHA VALUES (6, 'PRANCHA', '5.9 a 6.0', '21 polegadas', '32L');
INSERT INTO PRANCHA VALUES (7, 'PRANCHA', '6.0 a 6.4', '21 polegadas', '34L');
INSERT INTO PRANCHA VALUES (8, 'PRANCHA', '5.10 a 6.4', '20 polegadas', '30L');
INSERT INTO PRANCHA VALUES (9, 'PRANCHA', '5.10 a 6.4', '20 polegadas', '32L');
INSERT INTO PRANCHA VALUES (10, 'PRANCHA', '6.2 a 6.6', '21 polegadas', '32L');
INSERT INTO PRANCHA VALUES (11, 'PRANCHA', '6.4 a 6.8', '21 polegadas', '34L');
INSERT INTO PRANCHA VALUES (12, 'PRANCHA', '6.2 a 6.6', '20 polegadas', '30L');
INSERT INTO PRANCHA VALUES (13, 'PRANCHA', '6.2 a 6.6', '21 polegadas', '30L');
INSERT INTO PRANCHA VALUES (14, 'PRANCHA', '6.2 a 6.6', '21 polegadas', '34L');
INSERT INTO PRANCHA VALUES (15, 'PRANCHA', '6.2 a 6.6', '21 polegadas', '36L');
INSERT INTO PRANCHA VALUES (16, 'PRANCHA', '6.2 a 6.6', '21 polegadas', '38L');
INSERT INTO PRANCHA VALUES (17, 'PRANCHA', '6.2 a 7.0', '21 polegadas', '34L');
INSERT INTO PRANCHA VALUES (18, 'PRANCHA', '6.2 a 7.0', '21 polegadas', '38L');
INSERT INTO PRANCHA VALUES (19, 'PRANCHA', '5.5 a 5.8', '18 polegadas', '23L');
INSERT INTO PRANCHA VALUES (20, 'PRANCHA', '5.8 a 5.10', '18 polegadas', '24L');
INSERT INTO PRANCHA VALUES (21, 'PRANCHA', '5.10', '18 polegadas', '27L');
INSERT INTO PRANCHA VALUES (22, 'PRANCHA', '6.0 a 6.2', '19 polegadas', '28L');
INSERT INTO PRANCHA VALUES (23, 'PRANCHA', '6.0 a 6.2', '19 polegadas', '29 a 31L');
INSERT INTO PRANCHA VALUES (24, 'PRANCHA', '5.10 a 6.0', '19 polegadas', '24L');
INSERT INTO PRANCHA VALUES (25, 'PRANCHA', '5.10', '19 polegadas', '26L');
INSERT INTO PRANCHA VALUES (26, 'PRANCHA', '6.0', '19 polegadas', '27L');
INSERT INTO PRANCHA VALUES (27, 'PRANCHA', '6.0', '19 polegadas', '29L');
INSERT INTO PRANCHA VALUES (28, 'PRANCHA', '6.2', '20 polegadas', '30 a 31L');
INSERT INTO PRANCHA VALUES (29, 'PRANCHA', '6.0', '19 polegadas', '25L');
INSERT INTO PRANCHA VALUES (30, 'PRANCHA', '6.0', '19 polegadas', '28L');
INSERT INTO PRANCHA VALUES (31, 'PRANCHA', '6.0', '19 polegadas', '30L');
INSERT INTO PRANCHA VALUES (32, 'PRANCHA', '6.0 a 6.2', '20 polegadas', '30 a 31L');
INSERT INTO PRANCHA VALUES (33, 'PRANCHA', '5.11', '19 polegadas', '26L');
INSERT INTO PRANCHA VALUES (34, 'PRANCHA', '5.11', '19 polegadas', '28L');
INSERT INTO PRANCHA VALUES (35, 'PRANCHA', '6.0', '20 polegadas', '29L');
INSERT INTO PRANCHA VALUES (36, 'PRANCHA', '6.1', '20 polegadas', '30L');
INSERT INTO PRANCHA VALUES (37, 'PRANCHA', '6.1 a 6.6', '20 polegadas', '30 a 31L');
INSERT INTO PRANCHA VALUES (38, 'PRANCHA', '6.1', '19 polegadas', '27L');
INSERT INTO PRANCHA VALUES (39, 'PRANCHA', '6.1', '19 polegadas', '28L');
INSERT INTO PRANCHA VALUES (40, 'PRANCHA', '6.1 a 6.3', '20 polegadas', '29L');
INSERT INTO PRANCHA VALUES (41, 'PRANCHA', '6.1 a 6.4', '20 polegadas', '31L');
INSERT INTO PRANCHA VALUES (42, 'PRANCHA', '6.2 a 6.6', '20 polegadas', '31L');
In my form, visually they are all of height and weight exact values. However, the value of the fields are the values of my reference table:
HEIGHT:
<option value="1,71 - 1,80m">1.71m</option>
<option value="1,71 - 1,80m">1.72m</option>
<option value="1,71 - 1,80m">1.73m</option>
<option value="1,71 - 1,80m">1.74m</option>
<option value="1,71 - 1,80m">1.75m</option>
<option value="1,71 - 1,80m">1.76m</option>
WEIGHT:
<option value="81 - 90kg">88Kg</option>
<option value="81 - 90kg">89Kg</option>
<option value="81 - 90kg">90Kg</option>
<option value=">90kg">91Kg</option>
<option value=">90kg">92Kg</option>
<option value=">90kg">93Kg</option>
<option value=">90kg">94Kg</option>

Answer 1

First you have to tell us, given a user and some boards, what makes the "ideal" board(s). Then that gets translated to SQL.
PS
You are going to have to remove units from your values if you want your queries to talk about those values using comparisons or arithmetic. (And then you can store numbers using numerical types.) You are going to have to store ranges as pairs of columns if you want to mention their endpoints easily. Otherwise you will have to write things like
U.HEIGHT >= get_min_from_range_as_number(B.HEIGHT)
U.WEIGHT <= get_weight_as_number_without_units(B.WEIGHT)
where the functions are complex.
Say you want rows where:
user USERID has ideal board(s) BOARDID
You have to tell us what that means in terms of simpler things. Eg perhaps it means that:
(read U.ID as USERID, B.ID as BOARDID)
there exist values for U.NAME, U.HEIGHT, ..., B.WEIGHT where
user U.ID with name U.NAME ... has height U.HEIGHT...
AND board B.ID suits height between B.MINHEIGHT and B.MAXHEIGHT ...
AND U.HEIGHT >= B.MINHEIGHT AND U.HEIGHT <= B.MAXHEIGHT
AND (B.MINHEIGHT + B.MAXHEIGHT)/2 <= U.WEIGHT * 100
AND ...
OR ...
Now we need a query that returns the rows that make that statement template into a true statement.
Already User holds rows where:
user ID with name NAME ... has height HEIGHT ...
And Board holds rows where:
board ID suits height between MINHEIGHT and MAXHEIGHT ...
But the nature of SQL JOIN is that table1 t1JOINtable2 t2 holds the rows that satisfy the first table's statement template ANDed to the second's with parameters/columns prefixed by aliases and dots. So User U JOIN Board B holds rows where:
user U.ID with name U.NAME ... has height U.HEIGHT ...
AND board B.ID suits height between B.MINHEIGHT and B.MAXHEIGHT ...
And the nature of WHERE is that tableWHEREcondition holds the rows that satify table's statement template ANDed with condition. So
User U JOIN Board B
WHERE U.HEIGHT >= B.MINHEIGHT AND U.HEIGHT <= B.MAXHEIGHT
...
holds rows where:
user U.ID with name U.NAME ... has height U.HEIGHT ...
AND board B.ID suits height between B.MINHEIGHT and B.MAXHEIGHT ...
AND U.HEIGHT >= B.MINHEIGHT AND U.HEIGHT <= B.MAXHEIGHT
...
Then SELECT drops any unwanted parameters/columns. So user U.ID has ideal oard(s) B.ID holds rows where:
SELECT U.ID, B.ID
FROM User U JOIN Board B
WHERE U.HEIGHT >= B.MINHEIGHT AND U.HEIGHT <= B.MAXHEIGHT
...
SELECT also renames columns. So to get our overall query of the rows where user USERID has ideal board(s) BOARDID we need:
SELECT U.ID AS USERID, B.ID AS BOARDID
FROM User U JOIN Board B
WHERE U.HEIGHT >= B.MINHEIGHT AND U.HEIGHT <= B.MAXHEIGHT
...