SQL Server使用兩個表中的where條件連接兩個表

Question

我有兩個表clinical_study和location_countries，他們都有共同的NCT_ID（臨床試驗）字段，我必須從第一個表（性別）應用條件的兩個表中提取數據，然后在第二個表中檢查國家匹配，我成功地設法運行以下查詢，但它在國家領域我正在英國和其他國家

select 
clinical_study.NCT_ID, clinical_study.BRIEF_SUMMARY, clinical_study.STUDY_TYPE, clinical_study.GENDER, location_countries.COUNTRY
from clinical_study

inner join location_countries
ON clinical_study.NCT_ID=location_countries.NCT_ID

where clinical_study.GENDER LIKE'Male' or clinical_study.GENDER like 'Both'

and  location_countries.COUNTRY ='United Kingdom'

NCT_ID ..... BRIEF_SUMMARY ..... STUDY_TYPE .....性別..... COUNTRY

xys ........ xyz ............... xyz ............兩個.......英國

XYS ........ XYZ ............... XYZ ............男.......法國

xys ........ xyz ............... xyz ............男.......英國

XYS ........ XYZ ............... XYZ ............男.......瑞典

如果我在這里錯過了一個技巧，請你建議嗎？

Answer 1

看起來你需要添加一些括號

select 
    clinical_study.NCT_ID, clinical_study.BRIEF_SUMMARY, clinical_study.STUDY_TYPE, clinical_study.GENDER, location_countries.COUNTRY
from clinical_study
inner join location_countries
ON clinical_study.NCT_ID=location_countries.NCT_ID
where (clinical_study.GENDER LIKE'Male' or clinical_study.GENDER like 'Both')
and  location_countries.COUNTRY ='United Kingdom'

Answer 2

我認為AND優先於OR，所以它將首先進行評估。 因此，您可以使用括號來強制優先級。

  where (clinical_study.GENDER LIKE'Male' or clinical_study.GENDER like 'Both')
  and  location_countries.COUNTRY ='United Kingdom'

Answer 3

你的OR條款需要括號

where (clinical_study.GENDER LIKE'Male' or clinical_study.GENDER like 'Both')
and  location_countries.COUNTRY ='United Kingdom'