データベースに接続して物事を行うwinformを作成したいと考えています。開いたときに接続し、ユーザーがクリックした内容に基づいてクエリを作成する必要があります。ロード時に接続を開き、すべての異なるクラスからその接続にアクセスできるようにすることが最善の方法であるとは、100% 確信が持てません。ユーザーがボタンをクリックしてクエリを実行したときにDB接続を開く接続を機能させるためにテストを実行しましたが、DB接続の開始を InitializeComponent() 部分に移動し、コンポーネントから移動したいと思いますすでに確立されている接続を呼び出すだけです。
ケースバイケースで実行するように設定しましたが、これを行うためのより良い方法はありますか? 私はあなたができる/すべき唯一の方法でそれをやっていますか?
これがテストです
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
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);
}
}
}
}
クエリ.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;
}
}
}