当使用linq求和sum()时,如果某列数据为null,就会出现异常 使用下面的语句即可解决相关问题: db.TableModel.Where(w => w.ID == ID).Select(s=>s.SMoney).DefaultIfEmpty(0m).Sum(); 当smoney字段可为null,且数据行中存在NULL时,使用以上语句可默认为0,最终使求和正常.

using System; using System.Data; using System.Configuration; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Text; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using Syst

var result = fruit.GroupBy(i => i.date) .Select(i => new { date = i.Key, no_of_apple = i.Where(j => j.fruit_code == "apple").Sum(k => k.count), no_of_pear = i.Where(j => j.fruit_code == "pear").Sum(k => k.count) });

查询表达式中处理Null值 此示例演示如何处理源集合中可能的 null 值. 诸如 IEnumerable<T> 等对象集合可能包含值为 null 的元素. 如果源集合为 null 或包含值为 null 的元素,并且查询未处理 null 值,当您执行查询时将会引发 NullReferenceException. var query1 = from c in categories where c != null join p in products on c.ID equals (p == nu

mvc linq to sql,linq to entity,sum,null 昨天写了段sum的统计语句, decimal sums sums = ( from fac in db.Apply where  fa.state == 1 select fac.num ).Sum(), 然后一运行,报错 Message=The cast to value type 'System.Decimal' failed because the materialized value is null. Eit

原文地址:Linq——Count.Sum.Min.Max.Average作者:mousekitty Linq查询之Count.Sum.Min.Max.Average using System; using System.Data; using System.Configuration; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Text; us

You are given a binary tree in which each node contains an integer value. Find the number of paths that sum to a given value. The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to

需如下树节点求和 5  /  \ 4     8  /     /  \ 11  13    4 / \     /  \  7    2      5   1 JavaScript实现 window.onload = function() { var n1 = new TreeNode(1, null, null), n51 = new TreeNode(5, null, null), n2 = new TreeNode(2, null, null), n7 = new TreeNode(7,

var id; //... if (!id&& typeof (id) != "undefined" && id!= 0) { //id为null } else { //id不为null } 最笨的方法判断是否为null,防止出错

You are given a binary tree in which each node contains an integer value. Find the number of paths that sum to a given value. The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Find the total sum of all root-to-leaf numbers. For example, 1 / \ 2 3

LeetCode:Path Sum Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \

Two Sum I Given an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please

class TreeNode { int val; TreeNode left; TreeNode right; TreeNode(int x) { val = x; } } public class Solution { public int sumNumbers(TreeNode root) { if(root==null)return 0; return sumRoot(root,0); } private int sumRoot(TreeNode root, int sum) { if(

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 return true

都是考查DFS.经典回溯算法,问题在于我对该类型的代码不熟悉,目前以参考别人的代码,然后加上自己的实现为主,通过类似的题目加强理解. 一.给定一棵二叉树,判断是否存在从root到leaf的路径和等于给定值sum,存在返回true,否则返回false. 思路:DFS. 代码: private boolean ifExist = false; public boolean hasPathSum(TreeNode root, int sum) { dfs(root , sum , 0); return

题目: Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2). The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and (row2

/************************************************************************* > File Name: 23_FindPath.cpp > Author: Juntaran > Mail: JuntaranMail@gmail.com > Created Time: 2016年08月30日 星期二 20时49分34秒 ***********************************************

要求给定树,与路径和,判断是否存在从跟到叶子之和为给定值的路径.比如下图中,给定路径之和为22,存在路径<5,4,11,2>,因此返回true;否则返回false. 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 5思路递归,从跟到叶子判断,如果在叶子处剩下的给定值恰好为给定值,那么返回ture.参考代码 /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * T

题目: Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] 链接: http://leetc

https://oj.leetcode.com/problems/path-sum/ /** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public boolean hasPathSum(TreeNode root,