Linq to SQL C#-数字范围 [英] Linq to SQL C# - number range

问题描述

你好.我只是在学习c#，并且试图了解如何使用Linq查询SQL.我已经在vb中使用2个文本框，一个datagridview和一个commit按钮制作了一个应用程序，想知道用户输入一个最小数字(不能小于0)来从db中选择一行的代码是什么.一个文本框，然后在另一个文本框中输入一个最大数字(不能大于5).用户点击了Submit，它应该显示有效的行，其中包含该列的值介于他们在文本框中输入的2个数字之间.


这是我到目前为止所拥有的

我有一个文本框和一个搜索按钮，用于按姓氏搜索数据库.很好用.

我希望能够输入2个数字，然后单击我拥有的另一个搜索按钮(btnAverage)并获取平均值.

Hello there. I am just learning c# and I''m trying to understand how to query SQL with Linq. I have made an application in vb using 2 textboxes, a datagridview and a submit button and would like to know what the code is to select a row from a db by a user inputting a min number(which can be no lower than 0) into one textbox and inputting a max number(which can be no higher than 5) into another textbox. The user hits submit and it should show the valid rows contain the column that has a value in between the 2 numbers they input in the textboxes.


this is what I have so far

I have a textbox and a search button that searches the db by lastname. that functions just fine.

I would like to be able to enter the 2 numbers and click on the other search button I have(btnAverage) and get the average number.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace MasterDetailProject
{
    public partial class Details : Form
    {
        //ATTRIBUTES
        private BaseballDataContext database = new BaseballDataContext();
        private const double MIN_AVG = 0.000;
        private const double MAX_AVG = 1.000;
        //CONSTRUCTOR
        public Details()
        {
            InitializeComponent();
        }//end constrcutor
        private void Details_Load(object sender, EventArgs e)
        {
            txtLastName.Text = "Name";
          
        }//end Details_Load

        //METHODS
        private void RefreshContacts()
        {
            //show everything in db, sort by lastname, firstname - SHOWS EVERYONE IN AddressBook. just call whenever need be
            playerBindingSource.DataSource =
                from address in database.Players
                orderby address.LastName, address.FirstName
                select address;
            //go to the first result
            playerBindingSource.MoveFirst();
            //clear the find textbox
            txtLastName.Clear();
        }
 
        //EVENT HANDLER
        private void btnSearch_Click(object sender, EventArgs e)
        {
            playerBindingSource.DataSource =
                from PlayerID in database.Players
                where PlayerID.LastName.StartsWith(txtLastName.Text)
                orderby PlayerID.LastName, PlayerID.FirstName
                select PlayerID;
            playerBindingSource.MoveFirst();
        }//end btnSearch_Click
        private void btnAverage_Click(object sender, EventArgs e)
        {
            playerBindingSource.DataSource =
                from PlayerID in database.Players
                where PlayerID.BattingAverage.
           
        }//end btnAverage
    }//end class}//end namespace

有什么想法吗?

Any ideas?

推荐答案

您是说battingaverage值应该在min_avg和max_avg之间吗?像这样 ? :

do you mean that the battingaverage value should be between min_avg and max_avg ??? like this ? :

playerBindingSource.DataSource =
from PlayerID in database.Players
where PlayerID.BattingAverage > MIN_AVG & PlayerID.BattingAverage < MAX_AVG
select PlayerID;

这篇关于Linq to SQL C#-数字范围的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！