使用 GROUP BY 进行 SQL MERGE

Question

我必须执行 MERGE 语句，但在需要准备查询之前，此查询有一个包含一些字符串列和值的 group by ，因为我进行分组时，我不能包含主键。如果我无法提供主键，如何进行MERGE？

这是查询

SELECT Account,
       BillDate, 
       Name,
       SUM(ChargeAmount) AS ChargeAmount, 
       SUM(ChargeTaxes) AS ChargeTaxes,       
  FROM MyTempTable
 GROUP BY Account, BillDate, Name

现在我需要从该查询开始对我的表进行MERGE，但我没有 pk。

Answer 1

您可以将 GROUP BY 子句与 MERGE 一起使用。正如文档规定:

[ WITH <common_table_expression> [,...n] ]
MERGE 
    [ TOP ( expression ) [ PERCENT ] ] 
    [ INTO ] <target_table> [ WITH ( <merge_hint> ) ] [ [ AS ] table_alias ]
    USING <table_source> 
    ON <merge_search_condition>
    [ WHEN MATCHED [ AND <clause_search_condition> ]
        THEN <merge_matched> ] [...n ]
    [ WHEN NOT MATCHED [ BY TARGET ] [ AND <clause_search_condition> ]
        THEN <merge_not_matched> ]
    [ WHEN NOT MATCHED BY SOURCE [ AND <clause_search_condition> ]
        THEN <merge_matched> ] [...n ]
    [ <output_clause> ]
    [ OPTION ( <query_hint> [ ,...n ] ) ]    
;

table_source 可以位于:

<table_source> ::= 
{
    table_or_view_name [ [ AS ] table_alias ] [ <tablesample_clause> ] 
        [ WITH ( table_hint [ [ , ]...n ] ) ] 
  | rowset_function [ [ AS ] table_alias ] 
        [ ( bulk_column_alias [ ,...n ] ) ] 
  | user_defined_function [ [ AS ] table_alias ]
  | OPENXML <openxml_clause> 
  | derived_table [ AS ] table_alias [ ( column_alias [ ,...n ] ) ] 
  | <joined_table> 
  | <pivoted_table> 
  | <unpivoted_table> 
}

因此，您可以放置​​ GROUP BY 子句，就像您在问题中所做的那样:

MERGE INTO table2 AS TGT
USING
(
  SELECT Account,
       BillDate, 
       Name,
       SUM(ChargeAmount) AS ChargeAmount, 
       SUM(ChargeTaxes) AS ChargeTaxes
  FROM table1
 GROUP BY Account, BillDate, Name
) AS SRC
  ON  SRC.Account = TGT.Account AND
      SRC.Name = TGT.Name
WHEN NOT MATCHED THEN
  INSERT (Account, BillDate, Name, ChargeAmount, ChargeTaxes)
  VALUES (SRC.Account, SRC.BillDate, 
          SRC.Name, SRC.ChargeAmount, SRC.ChargeTaxes);

SQL Fiddle Demo