WHERE 子句忽略 LEFT OUTER JOIN 中的行

Question

我有三个table：

clinic = (id,name,short_name,region,country,continent,area) 
result_month =(id,year,result_quarter_id,month)
test_value_in_range_count =(clinic_id,result_month_id,patient_sub_set_id,test_value_range_id,number_of_values)

示例数据：

诊所

id      region      country     continent   area    
3299    Kazakhstan  Kazakhstan  Eurasia     Middle East/Asia

result_month

id      year    result_quarter_id   month   
200801  2008    2008Q1              1    

test_value_in_range_count

诊所 table 中没有诊所 ID 3299 的数据。但是 JOINS 必须 return

我需要 result_month table 中的所有行都包含 test_value_in_range_count 中的空行.问题是 WHERE 子句。这将停止生成行，因为从 result_month 到 test_value_range_id 的某些行显然不存在数据。

预期结果

clinic  region      country     continent   area                ym     vf
3299    Kazakhstan  Kazakhstan  Eurasia     Middle East/Asia    201511 null

我尝试了很多不同的查询，将它们分开但没有成功。任何帮助或指导将不胜感激。

     SELECT
          apc.id AS clinic,
          apc.region,
          apc.country,
          apc.continent,
          apc.area,
          vrm.id AS ym,

        SUM(CASE test_value_range_id WHEN '1124_1' THEN number_of_values ELSE 0 END) AS avf

    FROM result_month vrm
        LEFT JOIN  test_value_in_range_count vt on  vrm.id = vt.result_month_id 
        LEFT OUTER JOIN clinic apc on vt.clinic_id = apc.id

    WHERE (vt.test_value_range_id IN ('1124_1', '1124_2', '1124_3', '1124_4', '1124_5')) AND (vt.patient_sub_set_id = 'ALL')
    GROUP BY apc.id, 
        apc.region, 
        apc.country, 
        apc.continent,
        apc.area, 
        vrm.id   

        ; 

Answer 1

从 where 子句中删除条件并将其添加到 join：

SELECT
      apc.id AS clinic,
      apc.region,
      apc.country,
      apc.continent,
      apc.area,
      vrm.id AS ym,

    SUM(CASE test_value_range_id WHEN '1124_1' THEN number_of_values ELSE 0 END) AS avf

FROM result_month vrm
    LEFT JOIN  test_value_in_range_count vt on  vrm.id = vt.result_month_id and (vt.test_value_range_id IN ('1124_1', '1124_2', '1124_3', '1124_4', '1124_5')) AND (vt.patient_sub_set_id = 'ALL')
    LEFT OUTER JOIN clinic apc on vt.clinic_id = apc.id

GROUP BY apc.id, 
    apc.region, 
    apc.country, 
    apc.continent,
    apc.area, 
    vrm.id   

    ; 

否则 where 子句从您的 left join

生成 join