SQL 查询需要很长时间才能响应

Question

我有一个 SQL 查询，例如

SELECT c.Case_Id, c.Disease_Sub_Type_Id, p.MedRecNo 
FROM case1 c, patient p, episode e, personal_medical_history pmh, reproductive_history rh 
WHERE c.Age <> '12' AND c.horizontal_spread <> '21' AND c.Patient_Id = p.Patient_Id 
      AND e.Case_Id = c.Case_Id AND pmh.Patient_Id = p.Patient_Id 
      AND rh.Patient_Id = p.Patient_Id 
GROUP BY c.Case_Id`

当我使用上面的查询时，这会很快给出结果，但是当我使用 OR 作为条件时，如

SELECT c.Case_Id, c.Disease_Sub_Type_Id, p.MedRecNo 
FROM case1 c, patient p, episode e, personal_medical_history pmh, reproductive_history rh 
WHERE c.Age <> '12' OR c.horizontal_spread <> '21' AND c.Patient_Id = p.Patient_Id AND e.Case_Id = c.Case_Id AND pmh.Patient_Id = p.Patient_Id 
      AND rh.Patient_Id = p.Patient_Id 
GROUP BY c.Case_Id`

我没有得到输出并且 MySQL 挂起。是否有任何简单的方法来申请加入或我的方法是错误的？

Answer 1

尝试像这样将 OR 括在括号中；

SELECT c.Case_Id
    ,c.Disease_Sub_Type_Id
    ,p.MedRecNo
FROM case1 c
    ,patient p
    ,episode e
    ,personal_medical_history pmh
    ,reproductive_history rh
WHERE (c.Age <> '12'
    OR c.horizontal_spread <> '21')
    AND c.Patient_Id = p.Patient_Id
    AND e.Case_Id = c.Case_Id
    AND pmh.Patient_Id = p.Patient_Id
    AND rh.Patient_Id = p.Patient_Id
GROUP BY c.Case_Id`

SQL 查询需要很长时间才能响应

SQL query takes lot of time to respond

mysql

sql-server

query-builder