C#数据库连接问题，路过的懂的话帮忙看看

Question

String constr = @"Data Source=***********;Initial Catalog=" + kuming + ";User ID=sa;Password=***************;MultipleActiveResultSets=true";
SqlConnection con = new SqlConnection(constr);

con.Open();
string sql = "select * from DH_HH where name='" + username + "' and mima='" + password + "'";
SqlCommand com = new SqlCommand(sql, con);
SqlDataReader reader = com.ExecuteReader();
if (reader.Read())
{
string SQL = @"update DH_HH set mima='" + passnew + "' where name='" + username + "'";
SqlCommand coms = new SqlCommand(SQL,con);
if (coms.ExecuteNonQuery() == 1)
xiugai = "true";
}
reader.Close();//关闭执行
con.Close();//关闭数据库连接//

                            false'System.InvalidOperationException: ExecuteReader requires an open and available Connection. The connection's current state is closed. at System.Data.SqlClient.SqlCommand.ValidateCommand(String method, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader() at WebService1.Service1.yanzheng(String json) in c:\Users\Administrator\Desktop\android\C#webservice\WebServiceHYWT\WebService1\Service1.asmx.cs:line 168'


                                                            第一个if语句为168行

Answer 1

建议你看下我的博客有篇文章专门讲了这个：http://blog.csdn.net/zhang_guyuan/article/details/53141482