SQL 当至少有一个值等于 value 然后设置为 value 的情况

Question

我正在尝试通过查询教授学位的不同值来更新表格。 faculty 表有一个 terminal degree 字段（值 Y 或 N）。 教授可以拥有多个学位，但如果至少有一行的最终学位 = Y，我想将该值设置为“Terminal”。 如果只有“N”的值，而没有“Y”的值，那么我想将终端度数设置为“非终端”

下面是我目前拥有的代码，但它不适用于拥有超过一个学位（Y 或 N 值）的教授

 UPDATE SNP_FACULTY_CENSUS SFC
    SET TERMINAL_DEGREE = (  
        Case
            WHEN EXISTS (SELECT DISTINCT(F.TERMINAL_DEGREE) 
                             FROM FACULTY F
                                left JOIN SNP_FACULTY_CENSUS S
                                ON F.PERSON_SKEY = S.PERSON_sKEY
                             )
                    THEN (SELECT  -- USE TERMINAL VALUE FROM FACULTY TABLE
                           CASE
                                 WHEN F.TERMINAL_DEGREE = 'Y' AND F.TERMINAL_DEGREE = ''--if at least ONE value equals Y
                                 THEN
                                     'Terminal'
                                WHEN F.TERMINAL_DEGREE = 'Y' -- if all values equal Y
                                 THEN 'Terminal'     
                                 WHEN F.TERMINAL_DEGREE = 'N' --if ALL values equal N    
                                 THEN
                                     'Not terminal'
                                 ELSE
                                     'Unknown'
                            END
                          FROM FACULTY F
                            left JOIN SNP_FACULTY_CENSUS S
                                ON F.PERSON_SKEY = S.PERSON_sKEY)                        
        
    
        END 
     ) 
    WHERE SFC.OIR_FALL_TERM = 'Fall 2019'
    ;

Answer 1

你必须使用不存在，下面的查询应该有效，因为我没有样本数据，我无法测试它：

UPDATE SNP_FACULTY_CENSUS SFC
SET TERMINAL_DEGREE = (  
    Case
        WHEN EXISTS (SELECT DISTINCT F.TERMINAL_DEGREE 
                         FROM FACULTY F
                            left JOIN SNP_FACULTY_CENSUS S
                            ON F.PERSON_SKEY = S.PERSON_sKEY
                         )
                THEN (SELECT  -- USE TERMINAL VALUE FROM FACULTY TABLE
                       CASE
                             WHEN F.TERMINAL_DEGREE = 'Y' --if ONE value equals Y
                             THEN
                                 'Terminal'
                             WHEN F.TERMINAL_DEGREE = 'N' and not exists(select 1 from  FACULTY fa where F.PERSON_SKEY = fa.PERSON_sKEY and Fa.TERMINAL_DEGREE = 'N')--if ALL values equal N    
                             THEN
                                 'Not terminal'
                             ELSE
                                 'Unknown'
                        END
                      FROM FACULTY F
                        left JOIN SNP_FACULTY_CENSUS S
                            ON F.PERSON_SKEY = S.PERSON_sKEY)                        
    

    END 
 ) 
WHERE SFC.OIR_FALL_TERM = 'Fall 2019';