MySQL 8.0

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select version();


version()


8.0.17


CREATE TABLE tab
(
  t_id    INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
  t_key   INTEGER NOT NULL,
  t_name  VARCHAR(10) NOT NULL,
  t_value VARCHAR(10) NOT NULL
);
INSERT INTO tab (t_key, t_name, t_value)
VALUES

(75, 'Couleur', 'Bleu'),
(75, 'Taille', 'Grand'),
(75, 'Poids',  '20'),
(75, 'Teint',  'Y'),

(76, 'Couleur', 'Bleu'),
(76, 'Taille', 'Grand'),
(76, 'Poids',  '20'),
(76, 'Teint',  'Y'),

(77, 'Couleur', 'Bleu'),
(77, 'Taille', 'Grand'),
(77, 'Poids',  '20'),
(77, 'Teint',  'N');




;
SELECT t1.t_key AS "t1key", t1.t_name AS "t1name", t1.t_value AS "t1value",
       t2.t_key AS "t2key", t2.t_name AS "t2name", t2.t_value AS "t2value"
FROM tab t1
JOIN tab t2
ON t1.t_key != t2.t_key
  AND t1.t_name = t2.t_name
  AND t1.t_value = t2.t_value
ORDER BY t1.t_id, t2.t_id;


t1key
t1name
t1value
t2key
t2name
t2value


75
Couleur
Bleu
76
Couleur
Bleu

75
Couleur
Bleu
77
Couleur
Bleu

75
Taille
Grand
76
Taille
Grand

75
Taille
Grand
77
Taille
Grand

75
Poids
20
76
Poids
20

75
Poids
20
77
Poids
20

75
Teint
Y
76
Teint
Y

76
Couleur
Bleu
75
Couleur
Bleu

76
Couleur
Bleu
77
Couleur
Bleu

76
Taille
Grand
75
Taille
Grand

76
Taille
Grand
77
Taille
Grand

76
Poids
20
75
Poids
20

76
Poids
20
77
Poids
20

76
Teint
Y
75
Teint
Y

77
Couleur
Bleu
75
Couleur
Bleu

77
Couleur
Bleu
76
Couleur
Bleu

77
Taille
Grand
75
Taille
Grand

77
Taille
Grand
76
Taille
Grand

77
Poids
20
75
Poids
20

77
Poids
20
76
Poids
20


SELECT 
  DISTINCT LEAST(t1key, t2key) AS "lst", 
        GREATEST(t1key, t2key) AS "gst",
    COUNT(LEAST(t1key, t2key)) AS mn_c,
    COUNT(GREATEST(t1key, t2key)) AS mx_c
FROM
(

  SELECT t1.t_key AS "t1key", t1.t_name AS "t1name", t1.t_value AS "t1value",
         t2.t_key AS "t2key", t2.t_name AS "t2name", t2.t_value AS "t2value"
  FROM tab t1
  JOIN tab t2
  ON t1.t_key != t2.t_key
    AND t1.t_name = t2.t_name
    AND t1.t_value = t2.t_value
  ORDER BY t1.t_id, t2.t_id
)
AS t1
GROUP BY LEAST(t1key, t2key), GREATEST(t1key, t2key)
ORDER BY 1, 2, 3, 4;





lst
gst
mn_c
mx_c


75
76
8
8

75
77
6
6

76
77
6
6


SELECT COUNT(tab.t_key) FROM tab WHERE t_key = 75;


COUNT(tab.t_key)


4


SELECT 
  DISTINCT LEAST(t1key, t2key) AS "lst", 
        GREATEST(t1key, t2key) AS "gst",
  COUNT(LEAST(t1key, t2key)) AS "mn_c"
  -- COUNT(GREATEST(t1key, t2key)) AS mx_c
FROM
(

  SELECT t1.t_key AS "t1key", t1.t_name AS "t1name", t1.t_value AS "t1value",
         t2.t_key AS "t2key", t2.t_name AS "t2name", t2.t_value AS "t2value"
  FROM tab t1
  JOIN tab t2
  ON t1.t_key != t2.t_key
    AND t1.t_name = t2.t_name
    AND t1.t_value = t2.t_value
  ORDER BY t1.t_id, t2.t_id
)
AS t1
GROUP BY LEAST(t1key, t2key), GREATEST(t1key, t2key)
HAVING COUNT(LEAST(t1key, t2key))/2 = (SELECT COUNT(tab.t_key) FROM tab WHERE t_key = t1key)
ORDER BY 1, 2, 3;



lst
gst
mn_c


75
76
8

t1key	t1name	t1value	t2key	t2name	t2value
75	Couleur	Bleu	76	Couleur	Bleu
75	Couleur	Bleu	77	Couleur	Bleu
75	Taille	Grand	76	Taille	Grand
75	Taille	Grand	77	Taille	Grand
75	Poids	20	76	Poids	20
75	Poids	20	77	Poids	20
75	Teint	Y	76	Teint	Y
76	Couleur	Bleu	75	Couleur	Bleu
76	Couleur	Bleu	77	Couleur	Bleu
76	Taille	Grand	75	Taille	Grand
76	Taille	Grand	77	Taille	Grand
76	Poids	20	75	Poids	20
76	Poids	20	77	Poids	20
76	Teint	Y	75	Teint	Y
77	Couleur	Bleu	75	Couleur	Bleu
77	Couleur	Bleu	76	Couleur	Bleu
77	Taille	Grand	75	Taille	Grand
77	Taille	Grand	76	Taille	Grand
77	Poids	20	75	Poids	20
77	Poids	20	76	Poids	20