Question

我正在尝试使用CASE从带有子查询的dblink返回值。但是，结果并未显示出我的期望。而不是通过每个WHEN，它从第一个WHEN返回值（即使它不符合条件）。我确定这与我在子查询中使用CASE的方式有关。

我自己运行了子查询，它返回了预期的结果。

select su.shp_filter as "User_Type", su.shp_access_id as "RAD_ID", su.shp_name as "User_Name", rg.rad_stu_level as "Student_Level",
case
    when su.shp_filter = 'STU' then 
        case
            when rgd.rad_goal_value like 'HP%' then 'HP'
            when rgd.rad_goal_value like 'AS%' then 'AS'
            when rgd.rad_goal_value like 'BU%' then 'BU'
            when rgd.rad_goal_value like 'ED%' then 'ED'
            when rgd.rad_goal_value like 'TE%' then 'TE'
            when rgd.rad_goal_value like 'UN%' then 'UN'
            when rgd.rad_goal_value like 'KE%' then 'KE'
            when rgd.rad_goal_value like 'PH%' then 'PH'
            when rgd.rad_goal_value like 'OP%' then 'OP'
            when rgd.rad_goal_value like 'CP%' then 'CP'
        end
    when su.shp_filter in ('ADV','REG','DEAN','DEPT','ATHL') then
        case
            when exists (select pebempl.pebempl_orgn_code_home, su.shp_access_id, spriden.spriden_id from pebempl@dblink pebempl
            join spriden@gold.ferris.edu spriden
            on pebempl.pebempl_pidm=spriden.spriden_pidm
            join DWSCHEMA.SHP_USER_MST su
            on substr(su.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8)
            where spriden.spriden_change_ind is null
            and pebempl.pebempl_orgn_code_home like '11%') then 'Office 1'
            when exists (select pebempl.pebempl_orgn_code_home, su.shp_access_id, spriden.spriden_id from pebempl@dblink pebempl
            join spriden@gold.ferris.edu spriden
            on pebempl.pebempl_pidm=spriden.spriden_pidm
            join DWSCHEMA.SHP_USER_MST su
            on substr(su.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8)
            where spriden.spriden_change_ind is null
            and pebempl.pebempl_orgn_code_home like '21%') then 'Office 2'
            when exists (select pebempl.pebempl_orgn_code_home, su.shp_access_id, spriden.spriden_id from pebempl@dblink pebempl
            join spriden@gold.ferris.edu spriden
            on pebempl.pebempl_pidm=spriden.spriden_pidm
            join DWSCHEMA.SHP_USER_MST su
            on substr(su.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8)
            where spriden.spriden_change_ind is null
            and pebempl.pebempl_orgn_code_home like '22%') then 'Office 3'
            when exists (select pebempl.pebempl_orgn_code_home, su.shp_access_id, spriden.spriden_id from pebempl@dblink pebempl
            join spriden@gold.ferris.edu spriden
            on pebempl.pebempl_pidm=spriden.spriden_pidm
            join DWSCHEMA.SHP_USER_MST su
            on substr(su.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8)
            where spriden.spriden_change_ind is null
            and pebempl.pebempl_orgn_code_home like '31%') then 'Academic Affairs'
end "College"

Answer 1

哦-我想我知道您的问题。您的exists子查询根本没有加入外部查询，因此它们总是返回数百行。如果将SHP_USER_MST的每个实例重命名为su1，su2，su3等，将会更加清楚：

when su.shp_filter in ('ADV','REG','DEAN','DEPT','ATHL') then
    case
        when exists (select pebempl.pebempl_orgn_code_home, su1.shp_access_id, spriden.spriden_id from pebempl@dblink pebempl
            join spriden@gold.ferris.edu spriden
            on pebempl.pebempl_pidm=spriden.spriden_pidm
            join DWSCHEMA.SHP_USER_MST su1 
            on substr(su1.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8)
            where spriden.spriden_change_ind is null
            and pebempl.pebempl_orgn_code_home like '11%') then 'Office 1'
        when exists (select pebempl.pebempl_orgn_code_home, su2.shp_access_id, spriden.spriden_id from pebempl@dblink pebempl
            join spriden@gold.ferris.edu spriden
            on pebempl.pebempl_pidm=spriden.spriden_pidm
            join DWSCHEMA.SHP_USER_MST su2 
            on substr(su2.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8)
            where spriden.spriden_change_ind is null
            and pebempl.pebempl_orgn_code_home like '21%') then 'Office 2'

如果您在此处查看，则子查询中没有任何内容引用su中的当前行-因此，您正在检查子查询中是否存在任何用户。而且他们总是这样做，因此它总是返回“ Office 1”。

我认为您想要更多类似

when su.shp_filter in ('ADV','REG','DEAN','DEPT','ATHL') then
    case
        when exists (select pebempl.pebempl_orgn_code_home, su.shp_access_id, spriden.spriden_id from pebempl@dblink pebempl
            join spriden@gold.ferris.edu spriden
            on pebempl.pebempl_pidm=spriden.spriden_pidm
            where spriden.spriden_change_ind is null
            and substr(su.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8) -- Link subquery to outer query
            and pebempl.pebempl_orgn_code_home like '11%') then 'Office 1'
        when exists (select pebempl.pebempl_orgn_code_home, su.shp_access_id, spriden.spriden_id from pebempl@dblink pebempl
            join spriden@gold.ferris.edu spriden
            on pebempl.pebempl_pidm=spriden.spriden_pidm
            where spriden.spriden_change_ind is null
            and substr(su.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8) -- Link subquery to outer query
            and pebempl.pebempl_orgn_code_home like '21%') then 'Office 2'
...etc

我认为这应该对您有用，但是作为其他建议，我认为您也可以重写该部分，以使其更有效率和可读性。

case (select substr(min(pebempl.pebempl_orgn_code_home),1,2) from pebempl@dblink pebempl
        join spriden@gold.ferris.edu spriden
        on pebempl.pebempl_pidm=spriden.spriden_pidm
        where spriden.spriden_change_ind is null
        and substr(su.shp_access_id,1,8) = substr(spriden.SPRIDEN_ID,1,8))
    when '11' then 'Office 1'
    when '21' then 'Office 2'
    when '22' then 'Office 3'
    when '31' then 'Academic Affairs'
end

使用CASE作为dblink的一部分来获取数据

1 个答案: