Winform连接数据库
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.Configuration; namespace winformlogin { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { #region using连接数据库 //string connStr = "Data Source=.\\SQLEXPRESS;Initial Catalog=MySchool;uid=sa;pwd=sa"; //string connStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString; string connStr = DBHelper.connStr; using (SqlConnection con = new SqlConnection(connStr)) { //string sql = string.Format("select count(1) from student where LogInId=‘{0}‘ and LogInPwd=‘{1}‘",user.Text,pwd.Text); //SqlCommand cmd = new SqlCommand(sql,con); string sql = string.Format("select count(1) from student where LogInId=@LogInId and LogInPwd=@LogInPwd"); SqlCommand cmd = new SqlCommand(sql,con); cmd.Parameters.AddWithValue("@LogInId",user.Text); cmd.Parameters.AddWithValue("@LogInPwd",pwd.Text); con.Open(); int n = Convert.ToInt32(cmd.ExecuteScalar()); if (n >= 1) { Form2 fr2 = new Form2(); fr2.Show(); this.Hide(); } else { MessageBox.Show("输入有误"); } } #endregion #region 使用异常处理机制 //string connStr = "Data Source=.\\SQLEXPRESS;Initial Catalog=MySchool;uid=sa;pwd=sa"; //SqlConnection con = new SqlConnection(connStr); //try //{ // con.Open(); // MessageBox.Show("连接数据库"); //} //catch (Exception ex) //{ // MessageBox.Show(ex.Message); //} //finally //{ // con.Close(); //} #endregion } private void button2_Click(object sender, EventArgs e) { string connStr = "Data Source=.\\SQLEXPRESS;Initial Catalog=MySchool;uid=sa;pwd=sa"; using (SqlConnection con = new SqlConnection(connStr)) { SqlCommand cmd = new SqlCommand("select count(1) from Student", con); con.Open(); int n = Convert.ToInt32(cmd.ExecuteScalar()); MessageBox.Show(n.ToString()); } } private void Form1_Load(object sender, EventArgs e) { } } }
以下是DBHelper.cs 类
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Configuration; namespace winformlogin { class DBHelper { public static string connStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString; public static string bankStr = ConfigurationManager.ConnectionStrings["bankStr"].ConnectionString; } }
以下是config文件:
<?xml version="1.0" encoding="utf-8" ?> <configuration> <connectionStrings> <add name="bankStr" connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=Bank;uid=sa;pwd=sa" providerName="System.Data.SqlClient"/> <add name="connStr" connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=MySchool;uid=sa;pwd=sa" providerName="System.Data.SqlClient"/> </connectionStrings> <startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" /> </startup> </configuration>
注意:还要在应用中引用 System.Configuration 引用
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