配置文件： <?xml version="1.0" encoding="utf-8" ?> <configuration> ? <connectionStrings> ??? <add name="Strcon" connectionString="Data Sourse=.\SQLEXPRESS;Initial Catalog=Province_City;Integrated Security=True"/> </connectionStrings> </configuration> DAL中sqlhelpe的： ?public static readonly string Strcon =??????????? ConfigurationManager.ConnectionStrings["Strcon"].ConnectionString; ?public static DataTable ExecuteDataTable(string cmdText,??????????? params SqlParameter[] parameters)??????? {??????????? using (SqlConnection conn = new SqlConnection(Strcon))??????????? {??????????????? conn.Open();??????????????? using (SqlCommand cmd = conn.CreateCommand())??????????????? {??????????????????? cmd.CommandText = cmdText;???????????? ??????????????????? cmd.Parameters.AddRange(parameters);??????????????????? using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))??????????????????? {??????????????????????? DataTable dt = new DataTable();??????????????????????? adapter.Fill(dt);??????????????????????? return dt;??????????????????? }??????????????? }??????????? }??????? } DAL中類的 ?class Province_City??? {??????? public static DataTable Getdata()??????? {??????????? string sql = "select * from Province_City where ParentID=@id";??????????? object i=0;??????????? return sqlhelper.ExecuteDataTable(sql,new SqlParameter("id",i));??????? }??? } 出現(xiàn)的問題是： DAL.sqlhelper”的類型初始值設定項引發(fā)異常。 是怎么回事？請教高手