<?xml version="1.0" encoding="utf-8" ?>
<configuration>
 <startup> 
 <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
 </startup>
 <appSettings>
 <!--数据库连接字符串-->
 <add key ="ConnString" value ="Data Source=.;initial Catalog=educ; user=sa; Password=123456;Pooling=true" />
 </appSettings>
</configuration>

namespace _03连接数据库
{
 class DataBaseHelper
 {

 /// 数据库打开连接的方法
 /// 
 /// </summary>
 /// <returns></returns>
 public static SqlConnection getSqlConnection()
 {
 SqlConnection sqlConnection = new SqlConnection(); 
 try
 {
 //获取数据库字符串
 sqlConnection.ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["ConnString"]; 
 sqlConnection.Open();
 sqlConnection.Close();
 }
 catch 
 {

 throw new Exception("无法连接数据库服务器"); 
 }
 
 return sqlConnection;
 }

 /// sql增删改的方法
 /// 
 /// </summary>
 /// <param name="sqlstr"></param>
 /// <returns></returns>
 public static int GetNonQueryEffect(string sqlstr)
 { 
 SqlConnection sqlConnection = new SqlConnection();
 try
 {
 sqlConnection.Open();
 //创建要执行的语句
 SqlCommand cmd = new SqlCommand(sqlstr, sqlConnection);
 return cmd.ExecuteNonQuery();//返回执行语句中的错误
 }
 catch (Exception ex)
 {
 throw new Exception(ex.ToString());
 
 }
 finally
 {
 sqlConnection.Close();
 sqlConnection.Dispose();//释放资源
 }
 
 }

 /// 读取数据的的方法 
 /// 
 /// </summary>
 /// <param name="sqlstr"></param>
 /// <returns></returns>
 public static DataSet GetDataset(string sqlstr)
 {
 SqlConnection conn = getSqlConnection();
 try
 {
 conn.Open();//打开数据库连接
 SqlDataAdapter sda = new SqlDataAdapter(sqlstr ,conn );//更新数据库的命令
 DataSet ds = new DataSet();
 sda.Fill(ds);//填充
 return ds;
 }
 catch (Exception ex)
 {

 throw new Exception(ex.ToString ());
 }
 finally
 {
 conn.Close();
 conn.Dispose();
 }
 } 
 }
}

private void Button_Click_1(object sender, RoutedEventArgs e)
 {
 string str = "select *FROM student";//查询的语句
 dataGrid.ItemsSource = DataBaseHelper.GetDataset(str).Tables[0].DefaultView;
 
 }
 private void Button_Click_2(object sender, RoutedEventArgs e)
 {
 if (txtuserName.Text.Trim()== " ")
 {
 return;
 }
 string strr = string.Format("select *FROM student where sname='{0}'", txtuserName.Text);
 dataGrid.ItemsSource = DataBaseHelper.GetDataset(strr).Tables[0].DefaultView;
 }