从数据库中删除满足条件的实体的最有效方法是什么? [英] What is the most effective way to delete entites that satisfy a condition from a database?

问题描述

AFAIK，没有直接的方法使用

AFAIK, there isn't a direct way to delete entities using a predicate such as

DbSet.RemoveWhere(() => {})

我尝试了几种删除方法，但不知道哪种方法最有效.你能指出我正确的方向吗?

I tried a few ways to delete and don't know which is the most efficient way to do it. Could you point me in the right direction?

我尝试过的第一件事也是最基本的事情:

The first and most basic thing I tried is:

_context.Users.RemoveRange(_context.Users.Where(u => u.Name.Equals("John")));

在删除之前将用户加载到内存中.我不喜欢这种方法.我尝试的第二种方法是使用 Z.EntityFramework.Plus 包:

which loads the user to the memory before deletion. I don't like this approach. The second way I tried is using the Z.EntityFramework.Plus package:

_context.Users.Where(u => u.Name.Equals("John")).Delete()

声称删除对象而不加载它们，但是我不知道这是否比第一种方法更好.同样，这感觉不对，因为efcore应该具有适当的方法来执行此操作.我第三次尝试是这样的:

which claims to delete objects without loading them but I don't know if this is better then the first way. Also this feels wrong as the efcore should have a proper way to do this. The third attempt I made was something like this:

_context.Users.Where(u => u.Name.Equals("John")).ForEachAsync(u => _context.Users.Remove(u));

我不知道这是否将用户加载到内存中，并且其中有一个讨厌的Async.它还给出了以下异常:

I don't know if this loads the users into the memory and it has a nasty Async in there. It also gives the following exception:

"Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack."

推荐答案

我认为 ExecuteSqlRaw 更适合您:

_context.Database.ExecuteSqlRaw("DELETE FROM Users WHERE Name = @p0", "John");

通常 Remove 和 RemoveRange 适用于您已经具有 Primary Key (通常是 Id )的情况对象，在这种情况下，您可以执行以下操作:

Generally Remove and RemoveRange are suitable for situations which you already have Primary Key (usually Id) of objects, in those cases you can do something like this:

_context.Users.Remove(new User {Id = id});

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