Python，將case語句插入sql查詢

Question

我在PYTHON的SQL查詢中多次使用CASE語句時遇到問題。 我想知道是否可以拿走CASE語句並創建一個模板，然後我可以將模板參數放回到原始查詢中。就像這樣：

case_stm_template = 
    crs.execute(""" 
     CASE 
      WHEN level_1 = 'Corporate' 
      THEN 
       CASE 
        WHEN ssr.rating = 'A' OR ssr.rating LIKE 'A[+-]' 
        THEN 'Corp A' 

        WHEN ssr.rating = 'AA' OR ssr.rating LIKE 'AA[+-]' 
        THEN 'Corp AA' 

        WHEN ssr.rating = 'BBB' OR ssr.rating LIKE 'BBB[+-]' 
        THEN 'Corp BBB' 

        ELSE NULL 
       END 

      WHEN level_1 = 'Government' AND level_2 = 'Provincial' 
      THEN 'Prov' 

      WHEN level_1 = 'Government' AND level_2 = 'Federal' 
      THEN 'Canada' 

      ELSE NULL 
     END 

     """) 

要把它放到

crs.execute(""" 
    SELECT 
     ... 
     case_stm_template, 
     SUM(...) 
    FROM .... 
    WHERE .... 
    GROUP BY 
     case_stm_template 
""".format(...)) 

這是行不通的。誰能幫我？謝謝！！！

Answer 1

什麼：

case_stm_template=""" 
    CASE 
     WHEN level_1 = 'Corporate' 
     THEN 
      CASE 
       WHEN ssr.rating = 'A' OR ssr.rating LIKE 'A[+-]' 
       THEN 'Corp A' 

       WHEN ssr.rating = 'AA' OR ssr.rating LIKE 'AA[+-]' 
       THEN 'Corp AA' 

       WHEN ssr.rating = 'BBB' OR ssr.rating LIKE 'BBB[+-]' 
       THEN 'Corp BBB' 

       ELSE NULL 
      END 

     WHEN level_1 = 'Government' AND level_2 = 'Provincial' 
     THEN 'Prov' 

     WHEN level_1 = 'Government' AND level_2 = 'Federal' 
     THEN 'Canada' 

     ELSE NULL 
    END 

    """ 

然後

crs.execute(""" 
SELECT 
    ... 
    %s, 
    SUM(...) 
FROM .... 
WHERE .... 
GROUP BY 
    %s 
""" % (case_stm_template, case_stm_template)) 

或者類似的規定。