sql - 在同一个 SQL 查询中匹配多个值

Question

我有一个具有以下结构的表。

Table Name: CustomerStocks

Structure 
Name                     Varchar(25) 
StockSymbol              Varchar(4)

以下是表格内容示例

名称 股票代码

Sam    AAPL
Sam    AMZN
Sam    GOOG

Judy   AAPL
Judy   AMZN

Jen    AMZN

Brian  GOOG
Brian  MSFT

目标是给定一个客户名称，我如何找出具有类似投资组合的其他客户的列表。换句话说，必须存在原始客户的所有权益。

因此，如果我正在寻找与 Jen 相似的客户，那么结果将是 Judy 和 Sam。

如果我正在搜索具有类似 Judy 投资组合的客户，那么结果将是 Sam。

但是，如果我正在使用 Brian 的投资组合搜索客户，它可以不返回任何行或只返回 Brian。

这可能吗？如果是这样，我该如何编写一个 sql 查询来实现这一点？

任何帮助都非常感谢。

Answer 1

（稍后稍作调整……）

我没有测试过这个，但类似......

DECLARE @name VARCHAR(24) = 'Judy';

WITH cte_stocks AS (
    SELECT StockSymbol
    FROM CustomerStocks
    WHERE Name = @name
)
SELECT Name
FROM CustomerStocks cs
LEFT JOIN cte_stocks a ON cs.StockSymbol = a.StockSymbol
GROUP BY cs.Name
HAVING COUNT(DISTINCT a.StockSymbol) = (SELECT COUNT(1) FROM cte_stocks)

……可能会

Answer 2

这应该有效：

declare @Name varchar(25) = 'Judy'

select * from CustomerStocks cs
where cs.StockSymbol in 
    (select x.StockSymbol 
     from CustomerStocks x 
     where x.Name = @Name)

或者排除 Judy：

declare @Name varchar(25) = 'Judy'

select * from CustomerStocks cs
where cs.StockSymbol in 
    (select x.StockSymbol 
     from CustomerStocks x 
     where x.Name = @Name
     and x.Name <> cs.Name)

Answer 3

好的，那么这个怎么样：

declare @Name Varchar(25) = 'Judy'
declare @table (StockSymbol varchar(4))

--Get StockSymbols to search for
insert into @table
select cs.StockSymbol 
from CustomerStocks cs 
where cs.Name = @Name
group by cs.StockSymbol


--Match against the people
select cs.Name from CustomerStocks cs
where (select count(*) 
     from CustomerStocks x 
     inner join @table t on x.StockSymbol = t.StockSymbol
     where x.Name = cs.Name
     group by x.StockSymbol) = (select count(*) from @table t)
group by cs.Name

Answer 4

像这样的东西可能会起作用，独立于引擎：

SELECT target.Name, 'similar_to', others.Name
FROM (
  SELECT Name, COUNT(*) numStocks
  FROM CustomerStocks
  GROUP BY Name
) target
  INNER JOIN (
    SELECT cs1.Name match, cs2.Name otherName, count(*) commonStocks
    FROM CustomerStocks cs1
      INNER JOIN CustomerStocks cs2
        ON cs1.StockSymbol = cs2.StockSymbol
          AND cs1.Name <> cs2.Name
    GROUP BY cs1.Name, cs2.Name
  ) others ON target.Name = others.match
      AND others.commonStocks >= numStocks.numStocks

Answer 5

带有NOT EXISTS()和EXCEPT运算符的选项

DECLARE @Name Varchar(25) = 'Judy'       
SELECT *
FROM dbo.CustomerStocks s
WHERE NOT EXISTS (
                  SELECT s3.StockSymbol
                  FROM dbo.CustomerStocks s3
                  WHERE s3.Name = @Name
                  EXCEPT
                  SELECT s2.StockSymbol
                  FROM dbo.CustomerStocks s2
                  WHERE s2.Name = s.Name                        
                  ) AND s.Name != @Name

为了提高性能，请使用此索引

CREATE INDEX ix_StockSymbol_CustomerStocks ON CustomerStocks(StockSymbol) INCLUDE(Name)

SQLFiddle上的演示