SQL多个连接

Question

给出以下两个表:

CREATE TABLE [dbo].[MTCorrelations]
(
    [CorrelationID] [int] IDENTITY(1,1) NOT NULL,
    [StockA] [nvarchar](5) NOT NULL,
    [StockB] [nvarchar](5) NOT NULL,
    [Correlation] [float] NOT NULL,
    [LengthStr] [nvarchar](5) NOT NULL,
    [Date] [datetime] NOT NULL
)

CREATE TABLE [dbo].[Industries]
(
    [IndustryID] [int] IDENTITY(1,1) NOT NULL,
    [Symbol] [nvarchar](5) NOT NULL,
    [Sector] [nvarchar](50) NULL,
    [Industry] [nvarchar](50) NULL
)

我试图从Industries表中查找StockA和StockB的行业.但是我不知道如何进行多个连接.这是我能想到的最好的:

SELECT TOP 1000 
[CorrelationID]

      ,[StockA]
      ,[StockB]
      ,[Correlation]
      ,b.Industry
      ,c.Industry
  FROM [MarketTopology].[dbo].[MTCorrelations] as a JOIN [MarketTopology].[dbo].[Industries] as b ON a.StockA = b.Symbol
  AND a JOIN [MarketTopology].[dbo].[Industries] as c ON a.StockB = c.Symbol

我在AND上收到错误.这样做的正确方法是什么？

Answer 1

删除AND a并只有下一个JOIN

SELECT TOP 1000  
          [CorrelationID],
          [StockA],
          [StockB],
          [Correlation],
          b.Industry,
          c.Industry   
  FROM [MarketTopology].[dbo].[MTCorrelations] AS a
  JOIN [MarketTopology].[dbo].[Industries] AS b 
    ON a.StockA = b.Symbol 
  JOIN [MarketTopology].[dbo].[Industries] AS c 
    ON a.StockB = c.Symbol