如何将2列sql结果组合成1

Question

我对这个很难过。我为emplid获得了两列sql结果，但不知道如何将它们组合成1.任何人都知道如何？我正在使用oracle。这是sql：

SELECT ee.emplid, mem.emplid
  FROM ps_employees ee, ps_vc_plan_mem mem
 WHERE     ee.empl_status IN ('A', 'L')
       AND ee.emplid NOT IN (SELECT vc.emplid
                               FROM ps_vc_plan_mem vc
                              WHERE vc.vc_plan_id in ('PNC-RS','PNC-SO','PNC-ESPP'))
       AND ee.emplid IN
              (SELECT srv.emplid
                 FROM ps_Z_ADD_EMP_SRVDT srv
                WHERE     srv.emplid = ee.emplid
                      AND srv.z_serv_dt_type = 'ESP'
                      AND service_dt <= (SELECT asofdate FROM psasofdate))
   OR mem.vc_plan_id in ('PNC-RS','PNC-SO','PNC-ESPP')

Answer 1

在这种情况下，您需要一个UNION，它是一个与另一个结果集（第二列）连接的结果集（第一列）。它看起来像这样：

SELECT ee.emplid
FROM ps_employees ee, ps_vc_plan_mem mem
WHERE     ee.empl_status IN ('A', 'L')
AND ee.emplid NOT IN (SELECT vc.emplid
                           FROM ps_vc_plan_mem vc
                          WHERE vc.vc_plan_id in ('PNC-RS','PNC-SO','PNC-ESPP'))
AND ee.emplid IN
          (SELECT srv.emplid
             FROM ps_Z_ADD_EMP_SRVDT srv
            WHERE     srv.emplid = ee.emplid
                  AND srv.z_serv_dt_type = 'ESP'
                  AND service_dt <= (SELECT asofdate FROM psasofdate))
OR mem.vc_plan_id in ('PNC-RS','PNC-SO','PNC-ESPP')
--Here's the use of UNION
UNION ALL
--Seond query is the same, just returning the "other" column
SELECT mem.emplid
FROM ps_employees ee, ps_vc_plan_mem mem
WHERE     ee.empl_status IN ('A', 'L')
AND ee.emplid NOT IN (SELECT vc.emplid
                           FROM ps_vc_plan_mem vc
                          WHERE vc.vc_plan_id in ('PNC-RS','PNC-SO','PNC-ESPP'))
AND ee.emplid IN
          (SELECT srv.emplid
             FROM ps_Z_ADD_EMP_SRVDT srv
            WHERE     srv.emplid = ee.emplid
                  AND srv.z_serv_dt_type = 'ESP'
                  AND service_dt <= (SELECT asofdate FROM psasofdate))
OR mem.vc_plan_id in ('PNC-RS','PNC-SO','PNC-ESPP')

如果您希望结果具有不同的值，请使用UNION代替UNION ALL，但除此之外，您已完全设定。

Answer 2

如果我遵循逻辑，您只想将当前的交叉连接拆分为单独的查询并将结果合并在一起;并且你可能会丢失其中一个过滤器，因为它是多余的：

SELECT ee.emplid,
  FROM ps_employees ee
 WHERE     ee.empl_status IN ('A', 'L')
       AND ee.emplid IN
              (SELECT srv.emplid
                 FROM ps_Z_ADD_EMP_SRVDT srv
                WHERE     srv.emplid = ee.emplid
                      AND srv.z_serv_dt_type = 'ESP'
                      AND service_dt <= (SELECT asofdate FROM psasofdate))
UNION ALL
SELECT mem.emplid
  FROM ps_vc_plan_mem mem
 WHERE mem.vc_plan_id in ('PNC-RS','PNC-SO','PNC-ESPP')

union消除了重复项，因此您无需明确排除下半部分出现的前半部分的值。

如果查询的任何一部分可以自己生成重复项 - 相同的ee.emplid可以出现两次，比如说 - 那么这也会抑制那些重复项。如果它们可以存在并且您想要显示它们，那么您需要使用union all代替，并且在这种情况下您可能希望恢复not exists子句。

Read more about the union operator

如果您想要一个整体计数，那么您可以将其包装为内联视图：

SELECT COUNT(*)
FROM (
    SELECT ee.emplid,
      FROM ps_employees ee
     WHERE     ee.empl_status IN ('A', 'L')
           AND ee.emplid IN
                  (SELECT srv.emplid
                     FROM ps_Z_ADD_EMP_SRVDT srv
                    WHERE     srv.emplid = ee.emplid
                          AND srv.z_serv_dt_type = 'ESP'
                          AND service_dt <= (SELECT asofdate FROM psasofdate))
    UNION ALL
    SELECT mem.emplid
      FROM ps_vc_plan_mem mem
     WHERE mem.vc_plan_id in ('PNC-RS','PNC-SO','PNC-ESPP')
)