Indstil kryds i MySQL:en ren måde

Er en INNER JOIN (eller blot JOIN) ikke det kryds, du har brug for? Forudsat at du laver joinforbindelsen over de relevante fælles kolonner.

Derfor:

SELECT s1.id
  FROM (SELECT id
          FROM subject_attribute
         WHERE attribute = 'des_sen'
           AND numerical_value >= 2.0
       ) AS s1
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'tough'
          AND numerical_value >= 3.5
       ) AS s2
    ON s1.id = s2.id

Dette strækker sig til N forespørgsler (N> 2) rent og lineært.

SELECT s1.id
  FROM (SELECT id
          FROM subject_attribute
         WHERE attribute = 'des_sen'
           AND numerical_value >= 2.0
       ) AS s1
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'tough'
          AND numerical_value >= 3.5
       ) AS s2
    ON s1.id = s2.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'though'
          AND numerical_value = 14
       ) AS s3
    ON s1.id = s3.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'through'
          AND numerical_value != 45
       ) AS s4
    ON s1.id = s4.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'plough'
          AND numerical_value < 9
       ) AS s5
    ON s1.id = s5.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'cough'
          AND numerical_value < 5
       ) AS s6
    ON s1.id = s6.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'bucolic'
          AND numerical_value >= 3.5
       ) AS s7
    ON s1.id = s7.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'set'
          AND numerical_value BETWEEN 0.23 AND 3.0
       ) AS s8
    ON s1.id = s8.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'intelligent'
          AND numerical_value >= 0.001
       ) AS s9
    ON s1.id = s9.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'anal-retentive'
          AND numerical_value < 7
       ) AS s10
    ON s1.id = s10.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'magnificent'
          AND numerical_value = 35
       ) AS s11
    ON s1.id = s11.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'quantum'
          AND numerical_value >= 55
       ) AS s12
    ON s1.id = s12.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'thoughtfulness'
          AND numerical_value >= 350.237
       ) AS s13
    ON s1.id = s13.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'calamity'
          AND numerical_value = 3.0
       ) AS s14
    ON s1.id = s14.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'pink'
          AND numerical_value > 0.5
       ) AS s15
    ON s1.id = s15.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'cornucopia'
          AND numerical_value BETWEEN 1 AND 12
       ) AS s16
    ON s1.id = s16.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'maudlin'
          AND numerical_value < 3.625
       ) AS s17
    ON s1.id = s17.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'triad'
          AND numerical_value >= 1.723
       ) AS s18
    ON s1.id = s18.id
  JOIN (SELECT id
          FROM subject_attribute
         WHERE attribute = 'ambient'
          AND numerical_value >= 3.1
       ) AS s19
    ON s1.id = s19.id