LinqToSql
不支持 IQueryable 主要出于使用习惯的优化考虑，因为当编写代码时，智能提示会出现一堆你不想使用的方法，如下图：
FreeSql 没想过支持 linq to sql 语法，原以为必须实现 IQueryable 才可以实现，结果一次惊喜，原来 ISelect 也行。
linq to sql 不需要实现 IQueryable，只要有对应的方法就成。
虽然支持了，但是还请使用 链式 + lambda 吧！！！
这次功能更新，为 ISelect 增加了 5个方法，对【链式 + lambda】的用户可能会造成少许影响，我在注释上标明了，如下图：
特别是 .Select() 方法，原先是没有支持了，这个功能放在了 ToList(a => new Dto{}) 合并来使用的。现在也可以使用 .Select()，需要避免一下坑：
-
请务必在 .ToList() 之前使用 .Select()；
-
请减少以上方法在【链式 + labmda】的模式下调用；
所有 ISelect 都可以使用类似以下的方法，包括 Repository、DbContext；
var t1 = (
from a in fsql.Select<Student>()
where a.id == item.id
select a
).ToList();var t1 = (
from a in fsql.Select<Student>()
where a.id == item.id
select new { a.id }
).ToList();var t1 = (
from a in fsql.Select<Student>()
where a.id == item.id
select new {
a.id,
a.name,
testsub = new {
time = a.age > 10 ? "大于" : "小于或等于"
}
}
).ToList();var t1 = (
from a in fsql.Select<Student>()
join b in fsql.Select<School>() on a.id equals b.StudentId
select a
).ToList();
var t2 = (
from a in fsql.Select<Student>()
join b in fsql.Select<School>() on a.id equals b.StudentId
select new { a.id, bid = b.id }
).ToList();
var t3 = (
from a in fsql.Select<Student>()
join b in fsql.Select<School>() on a.id equals b.StudentId
where a.id == item.id
select new { a.id, bid = b.id }
).ToList();var t1 = (
from a in fsql.Select<Student>()
join b in fsql.Select<School>() on a.id equals b.StudentId into temp
from tc in temp.DefaultIfEmpty()
select a
).ToList();
var t2 = (
from a in fsql.Select<Student>()
join b in fsql.Select<School>() on a.id equals b.StudentId into temp
from tc in temp.DefaultIfEmpty()
select new { a.id, bid = tc.id }
).ToList();
var t3 = (
from a in fsql.Select<Student>()
join b in fsql.Select<School>() on a.id equals b.StudentId into temp
from tc in temp.DefaultIfEmpty()
where a.id == item.id
select new { a.id, bid = tc.id }
).ToList();var t1 = (
from a in fsql.Select<Student>()
from b in fsql.Select<School>()
where a.id == b.StudentId
select a
).ToList();
var t2 = (
from a in fsql.Select<Student>()
from b in fsql.Select<School>()
where a.id == b.StudentId
select new { a.id, bid = b.id }
).ToList();
var t3 = (
from a in fsql.Select<Student>()
from b in fsql.Select<School>()
where a.id == b.StudentId
where a.id == item.id
select new { a.id, bid = b.id }
).ToList();var t1 = (
from a in fsql.Select<Student>()
where a.id == item.id
group a by new {a.id, a.name } into g
select new {
g.Key.id, g.Key.name,
cou = g.Count(),
avg = g.Avg(g.Value.age),
sum = g.Sum(g.Value.age),
max = g.Max(g.Value.age),
min = g.Min(g.Value.age)
}
).ToList();