问题描述
我有一个数据库,其中有几个表使用关联链接。是否可以查询数据库以使用关联从表中提取记录?看下面的代码?
我试图从所有三个表中获取值,即从表BOOK提取P_C和STRIKE,从表OPTIONS提取OPT_MULTIPLIER和OPT_EXPIRY,最后从表SKEW提取SKEW_A 。
我可以获得一层下来的记录,但我不知道如何从两个表格中获取记录。这里http://imgur.com/D7kh1oE是映射图像的链接。
我尝试过:
I have a database with several tables linked using associations. Is it possible to query the database to extract records from tables two tiers down using the association? See code below?
I am trying to get values from all three tables i.e from table BOOK extract P_C and STRIKE, from table OPTIONS extract OPT_MULTIPLIER and OPT_EXPIRY, and finally from table SKEW extract SKEW_A.
I can get records one tier down, but I don't know how to get records from a table two tiers down. Here "http://imgur.com/D7kh1oE" is a link to the mapping image.
What I have tried:
using (lnkTRADERDataContext DATActx = new lnkTRADERDataContext())
{
var qryBOOK = from B in DATActx.BOOKs where B.DEAL == 1
select new clsTRADER()
{
P_C = B.P_C, //main table
STRIKE = B.STRIKE, //main table
OPT_EXP = B.OPTIONs.Single(X => X.OPT_EXPIRY), //one tier down
OPT_MULT = B.OPTIONs.Single(X => X.OPT_MULTIPLIER), //one tier down
SKEW_A = B.OPTIONs.SKEWs.Single(X => X.SKEW_A) // two tiers down
};
}
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