Sql server 具有多个条件的SQL多重选择

我有一个数据表“债券价格”，其值如下：

date     | type | price  
1/5/2019   bid    104.50  
1/5/2019   bid    104.75
1/6/2019   bid    104.40  
1/6/2019   bid    104.45   
1/5/2019   offer  106.75   
1/5/2019   offer  107.75
1/6/2019   offer  106.23
1/6/2019   offer  106.47

我想编写一个查询，给出给定日期的出价最高价格和出价最低价格，如以下输出：

date     | Highest Bid | Lowest Offer
1/5/2019   104.75        106.75
1/6/2019   104.45        106.23

我可以通过这样做获得最高出价或最低出价

SELECT "date", max("price") AS "Highest Bid"
FROM "BondPrices" 
WHERE "type"='bid' 
GROUP BY "date"

或

但是，当我尝试将它们组合在一起（例如使用JOIN）时，会出现语法错误

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如何使用多个条件编写select语句，从而产生多个列？

这里有几种方法可以剥猫皮，这将使您达到以下目的：

SELECT
    CAST(date AS DATE) Date,
    MAX(CASE WHEN type = 'bid' THEN price ELSE NULL END) HighestBid,
    MIN(CASE WHEN type = 'offer' THEN price ELSE NULL END) LowestOffer
FROM 
    BondPrices
GROUP BY 
    CAST(date AS DATE)

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这里有几种剥猫皮的方法，这会让你达到目的：

SELECT
    CAST(date AS DATE) Date,
    MAX(CASE WHEN type = 'bid' THEN price ELSE NULL END) HighestBid,
    MIN(CASE WHEN type = 'offer' THEN price ELSE NULL END) LowestOffer
FROM 
    BondPrices
GROUP BY 
    CAST(date AS DATE)