SQL：使用 WHERE 子句连接表

Question

我正在尝试加入共享同一个人 ID (key) 的两个 table。第一个 table (a) 是一个 'wide' table，有很多变量，包括 key 和 age，第二个 table (b)是一个'long'table，只包含变量key、diagnosis_number和diagnosis，其中每个个体可以有多个值diagnosis.

我想要 select 列 key、age 以及以下个人的初步诊断：

diagnosis = "a"、"b" 或 "c" 当 diagnosis_number = 1 ['primary diagnosis']
AND diagnosis = "y" 对于任何 diagnosis_number = 2:20

我试过：

SELECT main.key, main.age, diag.diagnosis
FROM a as main

INNER JOIN
    
(

   SELECT prim.key, prim.diagnosis
   FROM

   (SELECT DISTICT key, diagnosis
    FROM b
    WHERE diagnosis IN ('a', 'b', 'c')
    AND diagnosis_number = 1) as prim

   INNER JOIN

   (SELECT DISTICT key, diagnosis
    FROM b
    WHERE diagnosis = 'y'
    AND diagnosis_number BETWEEN 2 AND 20) as sec

   ON prim.key = sec.key) as diag

ON main.key = diag.key

Answer 1

~~认为这可以在没有 subqueries/SELECTs 内部联接的情况下解决：~~

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SELECT a.key, a.age, b.diagnosis
FROM a
INNER JOIN b
    ON b.key = a.key
WHERE b.diagnosis IN ('a', 'b', 'c')
    AND b.diagnosis_code = 1
    AND a.key IN (SELECT b1.key 
                  FROM b AS b1
                  WHERE b1.diagnosis = 'y'
                      AND b1.diagnosis_code BETWEEN 2 AND 20)

SQL：使用 WHERE 子句连接表

SQL: Joining tables with WHERE clauses

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