使用 CASE 作为 dblink 的一部分来获取数据

Question

我正在尝试使用 CASE return 来自带有子查询的 dblink 的值。但是，结果并没有显示出我所期望的。它不是遍历每个 WHEN，而是 returning 从第一个 WHEN 开始的值（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。

我有运行子查询本身，它 return 是预期的结果。

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 - 我想我明白你的问题了。您的 exists 子查询根本没有连接到您的外部查询，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，这将更加清晰：

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'

如果您查看此处，子查询中没有任何内容引用 su 中的当前行 - 因此您正在检查您的子查询中是否存在任何用户。他们总是这样做，所以总是 returns 'Office 1'.

我想你想要更像

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

我认为这应该适合您，但作为附加建议，我认为您也可以重写该部分以提高效率和可读性。

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

Using CASE as part of a dblink to get data

sql

oracle

dblink

case