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C# linq group by 异常 -----MySqlException: Unknown column 'GroupBy1.K1' in 'field list'

摘要：使用Linq group by 查询一般我们都会这样写Linq：var result = (from si in model.table group si by si.NumCores into grp orderby grp.Key select new CoreCount { Cores = 阅读全文

posted @ 2020-06-21 01:33 淡然→笑阅读(384) 评论(0) 推荐(0)

System.InvalidOperationException: Unexpected connection state. When using a wrapping provider ensure that the StateChange event is implemented on the wrapped DbConnection.

摘要： System.InvalidOperationException: Unexpected connection state. When using a wrapping provider ensure that the StateChange event is implemented on the 阅读全文

posted @ 2020-06-11 16:58 淡然→笑阅读(1255) 评论(2) 推荐(0)

Attaching an entity of type 'xxx' failed because another entity of the same type already has the same primary key value

摘要： Attaching an entity of type 'xxx' failed because another entity of the same type already has the same primary key value. This can happen when using th 阅读全文

posted @ 2020-05-28 13:40 淡然→笑阅读(1897) 评论(0) 推荐(0)

EF保存数据报错：An entity object cannot be referenced by multiple instances of IEntityChangeTracker.

摘要： EF保存关联表报错：An entity object cannot be referenced by multiple instances of IEntityChangeTracker. 字面理解就是一个实例对象不能被多个IEntityChangeTracker实例对象引用因为使用了Autofa 阅读全文

posted @ 2020-05-28 10:51 淡然→笑阅读(333) 评论(0) 推荐(0)

SqlServer时间格式不足2位补0

摘要： CREATE FUNCTION [dbo].[FULL_TIME](@Times NVARCHAR(50)) RETURNS NVARCHAR(50) AS BEGIN DECLARE @return NVARCHAR(50) SET @return =( select case len(SUBST 阅读全文

posted @ 2020-05-26 18:29 淡然→笑阅读(1988) 评论(0) 推荐(0)

windows服务/winform中使用Autofac依赖注入

摘要：其实Windows服务使用autofac注入很简单，只需要简单的配置然后调用Build就可以。以下代码winform中同样可以用 /* .Net framework 4.5 Autofac 4.9.4.0 EF 6 App.config 中connectionStrings的配置和winform一样阅读全文

posted @ 2020-05-15 10:11 淡然→笑阅读(5207) 评论(2) 推荐(2)

C# Socket 处理拆包、粘包

摘要： 1、采用TCP自定义协议通讯，协议由02(byte) + json字符串(byte[]) +03(byte)组成。 Socket_Client.cs 服务端using System;using System.Collections.Generic;using System.Net;using Sys 阅读全文

posted @ 2020-05-09 15:16 淡然→笑阅读(1458) 评论(0) 推荐(0)

Autofac依赖注入之AuthorizeAttribute属性注入---.net framework 4.5 Mvc5 WebApi

摘要： 1、Webapi框架下使用Autofac属性注入之 AuthorizeAttribute的属性注入 public class MyAuthorizeAttribute : AuthorizeAttribute { public MyLog log { get; set; } //autofac注入的阅读全文

posted @ 2020-05-09 11:55 淡然→笑阅读(864) 评论(0) 推荐(0)

BitmapFactory.decodeStream返回null值，InputStream 被调用两次，第一次调用流被关闭清空了！！！

摘要： InputStream inputstrem =getContentResolver().openInputStream(图片Uri); //解码获取图片的宽高 BitmapFactory.Options options = new BitmapFactory.Options(); options. 阅读全文

posted @ 2020-04-13 15:13 淡然→笑阅读(850) 评论(0) 推荐(0)

Android Studio开发---Get Post Put Delete 封装okhttp3类

摘要： package com.example.xxxxxx.com;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Handler;import android.os.Messag 阅读全文

posted @ 2020-03-18 13:46 淡然→笑阅读(782) 评论(0) 推荐(0)

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