SQL到Linq：左联接

Question

我需要编写linq查询。我试图用sql编写示例，但效果很好，但我没有设法将其转换为正确的linq

这是我的工作SQL查询：

A[np.arange(len(b))[:,None],b[:,None] + np.arange(-(L//2),L//2+1)]

这是我的linq尝试：

mainBackground

Answer 1

您的linq不执行左连接和交叉连接 试试这个

var productsDesc = (from pr in context.Product.Where(m => m.Id == 123)
                                join prg in context.PrGroup
                                on pr.GroupId equals prg.Id
                                join pg in context.PrParamGroup
                                on pr.PrParamGroupId equals pg.Id into tmp1
                                from t1 in tmp1.DefaultIfEmpty()
                                from prm in context.PrParam
                                join px in context.PrParam2ProductX
                                on new { a = pr.Id, b = px.ProductId } equals new { a = prm.Id, b = px.PrParamId } into tmp2
                                from t2 in tmp2.DefaultIfEmpty()
                                join gx in context.PrParam2GroupX
                                on new { prm.Id = gx.PrParamId } equals new {  pg.Id = gx.PrParamGroupId } into tmp3
                                from t3 in tmp3.DefaultIfEmpty()
                                select new
                                {
                                    Name = prm.Descr,
                                    Value = t2.Value,
                                    Unit = prm.Unit ?? ""
                                }).ToList();