Đặt giao điểm trong MySQL:một cách sạch sẽ

Không phải là THAM GIA BÊN TRONG (hoặc đơn giản là THAM GIA) là điểm giao nhau mà bạn cần? Giả sử bạn thực hiện liên kết qua các cột chung có liên quan.

Do đó:

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

Điều này mở rộng đến N truy vấn (N> 2) một cách rõ ràng và tuyến tính.

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