在Winform中爲SqlConnection設置全局優化的方法

Question

我想創建一個連接到數據庫來執行操作的winform。它在打開時必須連接，然後根據用戶點擊的內容進行查詢。我不是100％確定加載時打開連接的最佳方法，並且可以從所有不同的類訪問連接。我做了一個測試運行，當用戶點擊按鈕然後進行查詢時，打開數據庫連接的連接工作，但我想將數據庫連接的開放移動到InitializeComponent（）部件，然後從組件只需撥打已建立的連接即可。

我已經設置好了，這樣它就可以在個案上運行，但有沒有更好的方法來做到這一點？我是這樣做的，只有你可以/應該這樣做？

下面是測試

Form1.Designer.cs

namespace end_of_day 
{ 
    using System.Data.SqlClient; 
    partial class Form1 
    { 
     /// <summary> 
     /// Required designer variable. 
     /// </summary> 
     private System.ComponentModel.IContainer components = null; 


     /// <summary> 
     /// Clean up any resources being used. 
     /// </summary> 
     /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param> 
     protected override void Dispose(bool disposing) 
     { 
      if (disposing && (components != null)) 
      { 
       components.Dispose(); 
      } 
      base.Dispose(disposing); 
     } 

     #region Windows Form Designer generated code 

     /// <summary> 
     /// Required method for Designer support - do not modify 
     /// the contents of this method with the code editor. 
     /// </summary> 
     private void InitializeComponent() 
     { 
      this.button1 = new System.Windows.Forms.Button(); 
      this.label1 = new System.Windows.Forms.Label(); 
      this.button2 = new System.Windows.Forms.Button(); 
      this.button3 = new System.Windows.Forms.Button(); 
      this.button4 = new System.Windows.Forms.Button(); 
      this.SuspendLayout(); 
      // 
      // button1 
      // 
      this.button1.Location = new System.Drawing.Point(78, 411); 
      this.button1.Name = "button1"; 
      this.button1.Size = new System.Drawing.Size(147, 64); 
      this.button1.TabIndex = 0; 
      this.button1.Text = "Test"; 
      this.button1.UseVisualStyleBackColor = true; 
      this.button1.Click += new System.EventHandler(this.button1_Click); 
      // 
      // label1 
      // 
      this.label1.AutoSize = true; 
      this.label1.Location = new System.Drawing.Point(13, 13); 
      this.label1.Name = "label1"; 
      this.label1.Size = new System.Drawing.Size(199, 13); 
      this.label1.TabIndex = 1; 
      this.label1.Text = "ERROR: didn\'t connect to the database."; 
      // 
      // button4 
      // 
      this.button4.Location = new System.Drawing.Point(78, 201); 
      this.button4.Name = "button4"; 
      this.button4.Size = new System.Drawing.Size(147, 64); 
      this.button4.TabIndex = 4; 
      this.button4.Text = "Print Out of Stock"; 
      this.button4.UseVisualStyleBackColor = true; 
      this.button4.Click += new System.EventHandler(this.button4_Click); 
      // 
      // Form1 
      // 
      this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); 
      this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; 
      this.ClientSize = new System.Drawing.Size(306, 523); 
      this.Controls.Add(this.button4); 
      this.Controls.Add(this.button3); 
      this.Controls.Add(this.button2); 
      this.Controls.Add(this.label1); 
      this.Controls.Add(this.button1); 
      this.Name = "Form1"; 
      this.Text = "End of day"; 
      this.ResumeLayout(false); 
      this.PerformLayout(); 

     } 

     #endregion 

     private System.Windows.Forms.Button button1; 
     private System.Windows.Forms.Label label1; 
     private System.Windows.Forms.Button button4; 
     // NOTE I NEED TO BE ABLE TO CHANGE THE LABEL FROM OTHER CLASSES FIX THIS SOMEHOW 
    } 
} 

Form1.cs的

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Windows.Forms; 
using System.Data.SqlClient; 
using System.Net.Mail; 

namespace end_of_day 
{ 
    public partial class Form1 : Form 
    { 
     public Form1() 
     { 
      InitializeComponent(); 
     } 

     private void button1_Click(object sender, EventArgs e) 
     { 
      SqlConnection myConnection = queries.create_concection(); 
      try 
      { 
       SqlDataReader myReader = null; 
       SqlCommand myCommand = new SqlCommand("SELECT TOP 100000 ItemName,Price,In_Stock,Vendor_Part_Num FROM Inventory", 
                 myConnection); 
       myReader = myCommand.ExecuteReader(); 

       String mess = ""; 
       int i = 0; 
       while (myReader.Read()) 
       { 
        if (i < 10) 
        { 

         mess += myReader["ItemName"].ToString(); 
         mess += myReader["Price"].ToString(); 
         mess += "\r\n"; 
        } 
        i++; 
       } 
      } 
      catch (Exception er) 
      { 

       DialogResult dlgRes = MessageBox.Show(er.ToString(), "Error", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question); 

      } 

     } 

     private void button4_Click(object sender, EventArgs e) 
     { 
      SqlConnection myConnection = queries.create_concection(); 

      DialogResult dlgRes = MessageBox.Show("Exculde Videos?", 
       "Options", 
       MessageBoxButtons.YesNoCancel, 
       MessageBoxIcon.Question); 

      String SQL_op = ""; 
      if (dlgRes == DialogResult.Yes) 
      { 
       SQL_op = "AND NOT Dept_ID = 'video'"; 
      } 


      try 
      { 

       SqlDataReader myReader = null; 
       SqlCommand myCommand = new SqlCommand("SELECT TOP 100000 ItemName,Price,In_Stock,Vendor_Part_Num FROM Inventory WHERE In_Stock<1 AND NOT Dept_ID = '006' "+ SQL_op+" ORDER BY Dept_ID", 
                 myConnection); 
       myReader = myCommand.ExecuteReader(); 

       String mess = ""; 
       int i = 0; 
       while (myReader.Read()) 
       { 
        if (i < 10) 
        { 

         mess += myReader["ItemName"].ToString(); 
         mess += myReader["Price"].ToString(); 
         mess += "\r\n"; 
        } 
        i++; 
       } 


       dlgRes = MessageBox.Show("Had " + i + "items including: \r\n" + mess, 
       "Confirm Document Close", 
       MessageBoxButtons.YesNoCancel, 
       MessageBoxIcon.Question); 

      } 
      catch (Exception er) 
      { 

       dlgRes = MessageBox.Show(er.ToString(), "Error", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question); 


      } 
     } 
    } 
} 

queries.cs

using System; 
using System.Collections.Generic; 
using System.Xml; 
using System.Linq; 
using System.Threading.Tasks; 
using System.Windows.Forms; 
using System.Data.SqlClient; 
using System.Web; 


namespace end_of_day 
{ 
    public class queries 
    { 
     public static SqlConnection create_concection() 
     { 
      Boolean hasConection =true; 
      SqlConnection myConnection = new SqlConnection(
       "Data Source=localhost\\SQLEXPRESS;" + 
       "Trusted_Connection=true;" + 

       "Initial Catalog=TESTDB; " + 
       "connection timeout=30" 
      ); 
      try 
      { 
       myConnection.Open(); 
      } 

       catch (Exception er) 
       { 
        hasConection = false; 
        DialogResult dlgRes = MessageBox.Show(er.ToString(), "Error", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question); 
       } 


      if (hasConection) { 
       // THIS SHOULD CHANGE THE LABEL OF THE MAIN FORM 
       //Form1 form = new Form1(); 
       //form.MyMessage = "made it"; 
      } 
      return myConnection; 
     } 
    } 
} 

Answer 1

這是印度政府ng打開時必須連接，然後根據用戶點擊的內容進行查詢。 ... 我已經設置好了，這樣它就可以在一個個案的情況下運行，但有沒有 更好的方法來做到這一點？

還有絕對是更好的方法。是否不是當表單加載時打開一個連接，並將其保持打開狀態。

您應該始終遵循的經驗法則是僅在需要時纔打開連接，並在完成使用後立即關閉連接。這意味着在實踐中，只有在需要運行查詢（儘可能接近實際查詢執行）時纔打開它，然後在查詢完成後立即關閉連接。

我不是100％肯定，最好的辦法就是打開連接時 IT負載，使這一方面能夠從所有 不同類訪問

你問什麼關於如何設計你的應用程序，你會得到一個常見的答案是使用n層設計。你應該閱讀multitier architectures。