我对此有点新。好奇在以下情况会发生什么?LINQ to SQL推迟执行和实现
var q = //MY LINQ TO SQL QUERY.Select(...)
.........
.........
var c = q.Count();
.........
.........
var x = q.Where(....).Select(....);
var y = x.ToList();//or something such that forces materialization
var d = q.Count();//same as c
var e = x.Count();
var f = y.Count();
sql语句实际上有多少次访问数据库?一旦在Count()。再次在Where()?或者Linq保留Count()期间实现的内容?
或者它也取决于哪里(..)有什么?就像它再次引用数据库vs,它只是引用了作为'q'/或任何其他.net集合等的一部分获得的内容?
编辑:
更新我的代码以一对夫妇的其他情形。当你调用Count
它并没有实现整个数据集
q -no db trip
c -yes, but translates to aggregate qry - select Count(*) and not a result set (as per answer below)
x -no db trip. No matter what is written in the Where(..)
y - yes
d - yes - does not *reuse* c
e - yes - select count(*) EVEN THOUGH x already materized during y
f - no db trip