根据来自不同表的联接从同一表中获取多个值

Question

我有一个以下要求，我想多次使用同一表联接从表中获取多个值。 但是我无法获得理想的结果。

下面是我尝试过的查询，它给出了重复的记录，并且花了很多时间在整个集合上运行。 我尝试使用distinct，但是它花了很多时间，所以我不得不中止查询。

  SELECT 
HGHost.name AS HOST,
  HGDB.name        AS DATABASE,
  HGDB.dbms        AS DBMS,
  HGDB.server      AS INSTANCE,
  HGSCH.name       AS SCHEMA,
  HGTBL.name       AS "TABLE",
  HGCLM.name       AS "COLUMN",
  HGVAL.value    AS "HCDE",
  HGVAL1.value    AS "NOPI",
  HGVAL2.value    AS "Inf_CLAS"
FROM 
  XVIEW.XCATTR IGCCA INNER JOIN XVIEW.XCATTRSTRVAL HGVAL
  on IGCCA.RID=HGVAL.ofcustomattributeRID AND IGCCA.NAME = 'SURE_CLASS'
  INNER JOIN  XVIEW.XCATTRSTRVAL HGVAL1 
  ON IGCCA.RID =HGVAL1.ofcustomattributeRID  AND IGCCA.NAME = 'NO_CLASS'
  INNER JOIN XVIEW.XCATTRSTRVAL HGVAL2
  ON  IGCCA.RID =HGVAL2.ofcustomattributeRID  AND IGCCA.NAME= 'Info_class'
  INNER JOIN XVIEW.DBCLM HGCLM
  ON HGVAL.OBJECTRID = HGCLM.RID
  OR HGVAL1.OBJECTRID = HGCLM.RID
  OR HGVAL2.OBJECTRID = HGCLM.RID
  INNER JOIN XVIEW.PDRDATABASETABLE HGTBL
  ON HGCLM.ofdatabasetablerid = HGTBL.rid
  INNER JOIN XVIEW.PDRDATABASESCHEMA HGSCH
  ON HGTBL.ofdataschemarid      = HGSCH.rid
  INNER JOIN XVIEW.PDRDATABASE HGDB
  ON HGSCH.ofdatabaserid        = HGDB.rid
  INNER JOIN XVIEW.PDRHOSTSYSTEM HGHost
  ON HGDB.hostedbyrid           = HGHost.rid
  WHERE HGHost.name = 'PROD'
  AND HGDB.name <> 'teradata'

基本上，我希望基于XCATTR表中的联接条件，从该XCATTRSTRVAL获得HCDE，NOPI和Inf_clas的值。 让我知道是否清楚。 示例输出：（必须填充最后3个字段）

运行查询后，我得到两行如下。 我想将它们合并为一个。

Answer 1

如果您严格需要加入表XVIEW.XCATTRSTRVAL ，我想您可以在下面的查询中写-

SELECT HGHost.name AS HOST,
       HGDB.name        AS DATABASE,
       HGDB.dbms        AS DBMS,
       HGDB.server      AS INSTANCE,
       HGSCH.name       AS SCHEMA,
       HGTBL.name       AS "TABLE",
       HGCLM.name       AS "COLUMN",
       MAX(HGVAL.value)    AS "HCDE",
       MAX(CASE WHEN IGCCA.NAME = 'NO_CLASS' THEN HGVAL.value END) AS "NOPI",
       MAX(CASE WHEN IGCCA.NAME = 'Info_class' THEN HGVAL.value END) AS "Inf_CLAS"
FROM XVIEW.XCATTR IGCCA
INNER JOIN XVIEW.XCATTRSTRVAL HGVAL ON IGCCA.RID= HGVAL.ofcustomattributeRID 
                                    AND IGCCA.NAME IN ('SURE_CLASS', 'NO_CLASS', 'Info_class')
INNER JOIN XVIEW.DBCLM HGCLM ON HGVAL.OBJECTRID = HGCLM.RID
INNER JOIN XVIEW.PDRDATABASETABLE HGTBL ON HGCLM.ofdatabasetablerid = HGTBL.rid
INNER JOIN XVIEW.PDRDATABASESCHEMA HGSCH ON HGTBL.ofdataschemarid = HGSCH.rid
INNER JOIN XVIEW.PDRDATABASE HGDB ON HGSCH.ofdatabaserid = HGDB.rid
INNER JOIN XVIEW.PDRHOSTSYSTEM HGHost ON HGDB.hostedbyrid = HGHost.rid
WHERE HGHost.name = 'PROD'
AND HGDB.name <> 'teradata'
GROUP BY HGHost.name,
         HGDB.name,
         HGDB.dbms,
         HGDB.server,
         HGSCH.name,
         HGTBL.name,
         HGCLM.name

Answer 2

尝试这个：

SELECT
    HGHOST.NAME   AS HOST,
    HGDB.NAME     AS DATABASE,
    HGDB.DBMS     AS DBMS,
    HGDB.SERVER   AS INSTANCE,
    HGSCH.NAME    AS SCHEMA,
    HGTBL.NAME    AS "TABLE",
    HGCLM.NAME    AS "COLUMN",
    -- ADDED FOLLOWING AGGREGATE FUNCTIONS
    MAX(CASE
        WHEN IGCCA.NAME = 'SURE_CLASS' THEN HGVAL.VALUE
    END) AS "HCDE",
    MAX(CASE
        WHEN IGCCA.NAME = 'NO_CLASS' THEN HGVAL.VALUE
    END) AS "NOPI",
    MAX(CASE
        WHEN IGCCA.NAME = 'Info_class' THEN HGVAL.VALUE
    END) AS "Inf_CLAS"
FROM
    XVIEW.XCATTR IGCCA
    INNER JOIN XVIEW.XCATTRSTRVAL HGVAL ON IGCCA.RID = HGVAL.OFCUSTOMATTRIBUTERID
                                           AND IGCCA.NAME IN (
        'SURE_CLASS',
        'NO_CLASS',
        'Info_class'
    )
    INNER JOIN XVIEW.DBCLM HGCLM ON ( HGVAL.OBJECTRID = HGCLM.RID )
    INNER JOIN XVIEW.PDRDATABASETABLE HGTBL ON HGCLM.OFDATABASETABLERID = HGTBL.RID
    INNER JOIN XVIEW.PDRDATABASESCHEMA HGSCH ON HGTBL.OFDATASCHEMARID = HGSCH.RID
    INNER JOIN XVIEW.PDRDATABASE HGDB ON HGSCH.OFDATABASERID = HGDB.RID
    INNER JOIN XVIEW.PDRHOSTSYSTEM HGHOST ON HGDB.HOSTEDBYRID = HGHOST.RID
WHERE
    HGHOST.NAME = 'PROD'
    AND HGDB.NAME <> 'teradata'
GROUP BY -- ADDED THIS GROUP BY
    HGHOST.NAME,
    HGDB.NAME,
    HGDB.DBMS,
    HGDB.SERVER,
    HGSCH.NAME,
    HGTBL.NAME,
    HGCLM.NAME;

干杯！！

Answer 3

您实际上是否需要多次连接到同一张表？

可以使用以下内容吗？ 您可能需要使用CASE语句替换IIF，具体取决于您的版本：

SELECT 
HGHost.name AS HOST,
  HGDB.name        AS DATABASE,
  HGDB.dbms        AS DBMS,
  HGDB.server      AS INSTANCE,
  HGSCH.name       AS SCHEMA,
  HGTBL.name       AS "TABLE",
  HGCLM.name       AS "COLUMN",
  IIF(IGCCA.NAME = 'SURE_CLASS',HGVAL.value,NULL)    AS "HCDE",
  IIF(IGCCA.NAME = 'NO_CLASS', HGVAL.value,NULL)    AS "NOPI",
  IIF(IGCCA.NAME = 'Info_class', HGVAL.value,NULL)    AS "Inf_CLAS"
FROM 
  XVIEW.XCATTR IGCCA
  INNER JOIN XVIEW.XCATTRSTRVAL HGVAL   on IGCCA.RID= HGVAL.ofcustomattributeRID AND IGCCA.NAME = 'SURE_CLASS'
  INNER JOIN XVIEW.DBCLM HGCLM
  ON HGVAL.OBJECTRID = HGCLM.RID
  INNER JOIN XVIEW.PDRDATABASETABLE HGTBL
  ON HGCLM.ofdatabasetablerid = HGTBL.rid
  INNER JOIN XVIEW.PDRDATABASESCHEMA HGSCH
  ON HGTBL.ofdataschemarid      = HGSCH.rid
  INNER JOIN XVIEW.PDRDATABASE HGDB
  ON HGSCH.ofdatabaserid        = HGDB.rid
  INNER JOIN XVIEW.PDRHOSTSYSTEM HGHost
  ON HGDB.hostedbyrid           = HGHost.rid
  WHERE HGHost.name = 'PROD'
  AND HGDB.name <> 'teradata'

Answer 4

大多数DBMS不喜欢OR ed连接条件，在Teradata中，它总是会导致（可能性能不佳） 产品/交叉连接 。 这也是行太多的原因，请尝试改写为三个联接：

SELECT 
  HGHost.name AS HOST,
  HGDB.name        AS DATABASE,
  HGDB.dbms        AS DBMS,
  HGDB.server      AS INSTANCE,
  HGSCH.name       AS SCHEMA,
  HGTBL.name       AS "TABLE",
  HGCLM.name       AS "COLUMN",
  HGVAL.value    AS "HCDE",
  HGVAL1.value    AS "NOPI",
  HGVAL2.value    AS "Inf_CLAS"
FROM 
  XVIEW.XCATTR IGCCA
INNER JOIN XVIEW.XCATTRSTRVAL HGVAL
  ON IGCCA.RID= HGVAL.ofcustomattributeRID
 AND IGCCA.NAME = 'SURE_CLASS'
INNER JOIN XVIEW.DBCLM HGCLM
  ON  HGVAL.OBJECTRID = HGCLM.RID
INNER JOIN  XVIEW.XCATTRSTRVAL HGVAL1 
  ON IGCCA.RID=HGVAL1.ofcustomattributeRID
 AND IGCCA.NAME = 'NO_CLASS'
INNER JOIN XVIEW.DBCLM HGCLM1
  ON HGVAL1.OBJECTRID = HGCLM1.RID
INNER JOIN XVIEW.XCATTRSTRVAL HGVAL2
  ON IGCCA.RID=HGVAL2.ofcustomattributeRI
 AND IGCCA.NAME= 'Info_class'
INNER JOIN XVIEW.DBCLM HGCLM2
  ON HGVAL2.OBJECTRID = HGCLM2.RID
INNER JOIN XVIEW.PDRDATABASETABLE HGTBL
  ON HGCLM.ofdatabasetablerid = HGTBL.rid
INNER JOIN XVIEW.PDRDATABASESCHEMA HGSCH
  ON HGTBL.ofdataschemarid    = HGSCH.rid
INNER JOIN XVIEW.PDRDATABASE HGDB
  ON HGSCH.ofdatabaserid      = HGDB.rid
INNER JOIN XVIEW.PDRHOSTSYSTEM HGHost
  ON HGDB.hostedbyrid         = HGHost.rid
WHERE HGHost.name = 'PROD'
  AND HGDB.name <> 'teradata'