使用 ODBC、联接和分组依据的 SQL 查询

Question

我对下面的声明有疑问。查询的主要目的是将客户列表从 ODBC 提取到 Access 数据库中（我们的客户存储在 IBM i 上的 DB2 中）。该查询旨在查找超过 13 个月未交付 (RS2101F.DELDATE) 但尚未被抑制 (OM01U1.OM01068) 的客户 (OM01U1.OM01015)。我确实需要所有的列来研究设备和财务记录，所以我无法移除它们。不过，该声明是从几个表中提取的。我认为问题可能出在“Group By”上。当我收到结果时，我也得到了重复的出口 (OM01U1.OM01015)。我只需要看到最后一次交货日期 (RS2101F.DELDATE) 一次。请不要把我打得太糟，我没有创建这个查询，我只是继承了它。我知道这很遥远，而且可能有更好的方法来获取我需要的信息。我感谢任何帮助家伙！

SELECT
    OM01U1.OM01041 as Loc,
    OM01U1.OM01015 AS Outlet, 
    OM01U1.OM01945 AS OLTyp,
    OM01U1.OM01052 AS Outlet_Name,
    OM01U1.OM01054A AS Street_Number, 
    OM01U1.OM01054C AS Street_Name, 
    OM01U1.OM01055A AS City, 
    OM01U1.OM01055B AS State, 
    OM01U1.OM01106 AS Zip, 
    OM01U1.OM01058A AS Area_Code, 
    OM01U1.OM01058C AS Phone, 
    OM01U1.OM01037 AS Channel, 
    OM01U1.OM01926 AS USA_Type,
    OM01U1.OM01078 AS Key_Acct, 
    OM01U1.OM01110 AS TRDGRP,
    OM01U1.OM01034 AS Trade_Name, 
    OM01U1.OM01248 AS DTC,
    OM01U1.OM01073 AS Sales_Route, 
    OM01U1.OM01068 AS Sup_CDE, 
    OM01U1.OM01982 AS Sup_Reason, 
    OM01U1.OM01067 AS Sup_Date, 
    OM01U1.OM01065 AS Creation_DT, 
    OM01U1.OM01066 AS Update_DT, 
    OM01U1.OM01141 AS CAN_NUM,
    CF30_CNSTYP AS CF_CONTYP, 
    EC01_EQUNUM AS EC_EQUIP,
    EC01_PRMSLR AS EC_SUPPLIER, 
    EC01_EQUOWN AS EC_OWN_CD,
    EC01_EQUACY AS EC_ACCESSORY,
    EC01_EQUSPP AS EC_COMPONENT,
    EC01_SYSSTA AS EC_STATUS,
    EC01_ISTDAT AS EC_INSTALL_DT, 
    EC01_RSPPRN AS EC_PERSON, 
    EC01_LASMTCDAT AS EC_LAST_MNT_DT, 
    OC02_RNTCTCNUM AS OC_CONT_NUM, 
    OC02_RNTCTCSTA AS OC_CONT_STATUS, 
    OC02_BTONUM AS OC_BILL_TO, 
    RS2101F.DELDATE AS RS_LAST_DEL_DT
  FROM 
    CF30, EC01, OC02, OM01U1, RS2101F
  WHERE 
    OM01U1.OM01015 = RS2101F.OUTNUM

  GROUP BY
    RS2101F.DELDATE,
    OC02_BTONUM,
    OC02_RNTCTCSTA,
    OC02_RNTCTCNUM,
    OC02_OUTNUM,
    EC01_LASMTCDAT,
    EC01_RSPPRN,
    EC01_ISTDAT,
    EC01_EQUOWN,
    EC01_EQUACY,
    EC01_EQUSPP,
    EC01_SYSSTA,
    EC01_PRMSLR,
    EC01_EQUNUM,
    CF30_CNSTYP,
    OM01U1.OM01141,
    OM01U1.OM01066,
    OM01U1.OM01065,
    OM01U1.OM01067,
    OM01U1.OM01982,
    OM01U1.OM01068,
    OM01U1.OM01073,
    OM01U1.OM01248,
    OM01U1.OM01034,
    OM01U1.OM01110,
    OM01U1.OM01078,
    OM01U1.OM01926,
    OM01U1.OM01037,
    OM01U1.OM01058C,
    OM01U1.OM01058A,
    OM01U1.OM01106,
    OM01U1.OM01055B,
    OM01U1.OM01055A,
    OM01U1.OM01054C,
    OM01U1.OM01054A,
    OM01U1.OM01052,
    OM01U1.OM01945,
    OM01U1.OM01015,
    OM01U1.OM01041
  HAVING  RS2101F.DELDATE < 1110809
      AND OM01U1.OM01068<>'S' 

Answer 1

您有一个有效的查询，但您正在选择：

FROM CF30, EC01, OC02, OM01U1, RS2101F 

没有显式连接，只有一个隐式连接：

WHERE OM01U1.OM01015 = RS2101F.OUTNUM

这将导致问题。您能找到每个表中的哪些字段（列）与哪些字段（列）匹配吗？然后你可以说：

FROM OM01U1 
INNER JOIN RS2101F
ON OM01U1.OM01015 = RS2101F.OUTNUM

例如。

您可能还会发现添加派生表很有用：

SELECT OUTNUM, Max(RS2101F.DELDATE) FROM RS2101F

所以那将是：

FROM OM01U1 
INNER JOIN (
     SELECT OUTNUM, Max(RS2101F.DELDATE) 
     FROM RS2101F
     GROUP BY OUTNUM) As t
ON OM01U1.OM01015 = t.OUTNUM