Question

我有一个表客户，其中我有6个属性

CustomerID  CustomerName CustomerCity CustomerState DuplicateCustIND
1           Richard      Los Angeles  New York 
2           Jerome       Houston      Texas   
3           Paul         Los Angeles  New York

在上表中，Richard和Paul有两个重复的列值CustomerCity和CustomerState相同。在检查两个相似的列条件后，我想用Richard的客户ID更新保留列DuplicateCustIND。

直到现在我使用相关查询

Update Customer C1 set C1.DuplicateCustIND = (select CustomerID  from customers 
                                             where C3.CustomerCity = 
                                             C1.CustomerCity and
                                             C3.CustomerState = 
                                             C1.CustomerState)
where exists(
Select 1 from Customers C2 where
C2.CustomerCity = C1.CustomerCity and
C2.CustomerState = C1.CustomerState and 
C2.RowID<C1.RowID);

以上查询对我没有帮助。

Answer 1

以下查询可行。

merge INTO customers tgt USING
(SELECT   a.id,
    a.cname,
    a.ccity,
    a.cstate
  FROM customers a,
    (SELECT   ccity,
        cstate,
        COUNT(*)
      FROM customers b
      GROUP BY ccity,
        cstate
      HAVING COUNT(*) > 1
    ) b
  WHERE a.ccity  = b.ccity
    AND a.cstate = b.cstate
) src ON (tgt.id = src.id)
WHEN matched THEN
  UPDATE SET tgt.dcustid = src.id;

Answer 2

您可能依赖customerid并使用MERGE语句更新所有大于customerid城市和州的记录。

MERGE INTO customers t USING
  ( SELECT MIN(c1.CUSTOMERID) prim_id,
           c2.CUSTOMERID sec_id
   FROM Customers c1
   JOIN customers c2 ON C2.CustomerCity = C1.CustomerCity
   AND C2.CustomerState = C1.CustomerState
   AND C2.CustomerID > C1.CustomerID
   GROUP BY C1.CustomerCity,
            C1.CustomerState,
            c2.CUSTOMERID ) s ON (s.sec_id = t.CustomerID ) 
WHEN MATCHED THEN
UPDATE
SET t.DuplicateCustIND = s.prim_id;

SQLFiddle

检查两个条件后，将查询列复制到另一列的SQL查询

2 个答案: