使用Entity Framework和MySQL的随机顺序 [英] Random order with Entity Framework and MySQL

问题描述

摘要::我想找到一种使用Entity Framework和MySQL进行随机排序的方法(这很重要).该解决方案不应该使用原始sql查询或在从数据库中加载所有值之后进行排序.

Summary: I want to find a way to make random order with Entity Framework and MySQL (that's important). That solution shouldn't use raw sql queries or ordering AFTER loading all values from database.

我尝试过的事情:

我想到了使用NewGuid()从该答案进行随机排序的想法.

I took idea about using NewGuid() for random order from that answer.

代码:

var query = from e in context.Table
orderby Guid.NewGuid()
select e;
var test = query.FirstOrDefault();

总是抛出异常:

An error occurred while executing the command definition. See the inner exception for details.
Inner exception:
FUNCTION MyDatabase.NewGuid does not exist System.Exception {MySql.Data.MySqlClient.MySqlException}

似乎问题在于MySQL没有功能NewGuid().

Seems that problem is that MySQL doesn't have function NewGuid().

如何通过MySQL函数 RAND()而不是 NewGuid()进行订购.换句话说，如何在Entity Framework中使用自定义函数 RAND ?

How can I order by MySQL function RAND() instead of NewGuid(). In other words, how to use custom function RAND in Entity Framework?

推荐答案

似乎问题在于MySQL没有功能NewGuid().

Seems that problem is that MySQL doesn't have function NewGuid().

叫我懒，但是问题似乎是MySql没有名为NewGuid的函数.因此，最简单的解决方案不是在MySql中创建一个名为NewGuid的函数吗?

Call me lazy, but the problem seems to be that MySql does not have a function called NewGuid. So wouldn't the easiest solution be to create a function in MySql called NewGuid?

DELIMITER $$
CREATE DEFINER=`root`@`localhost` FUNCTION `NewGuid`() RETURNS char(36)
BEGIN
RETURN UUID();
END$$
DELIMITER ;

创建MySQL NewGuid函数后，问题已为我解决.

Problem is solved for me after creating a MySQL NewGuid function.

问题指出解决方案不应使用原始sql查询"，并且这不需要原始的SELECT/INSERT语句.确实需要创建数据库功能.

The Questions states "solution shouldn't use raw sql queries" and this does not require a raw SELECT/INSERT statement. It does require the database function to be created though.

特别注意:我要说的是，从技术上讲，这是MySQL实现中的错误.规范函数被称为由所有数据提供程序支持".NewGuid列在其他规范函数下

Extra note: I would say that this is technically a bug in the MySQL implementation. Canonical Functions are said to be "supported by all data providers" by Microsoft. NewGuid is listed under Other Canonical Functions

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