c# sql连接数据库

using System.Data.SqlClient;

private static string connectionString ="Data Source=.\\HS;Initial Catalog=sqltable;User ID=sa;pwd=0";

private SqlConnection ConnectionOpen()
{
SqlConnection conn = new SqlConnection(connectionString);
conn.Open();
return conn;
}
/// <summary>
/// 向表(Table)中插入一条数据
/// </summary>
public void Insert(int yid,string examtitle,int kemuD,int kemuX,int sort)
{

SqlConnection conn = ConnectionOpen();
//string sql =
// "insert into Table(row1, row2, row3, DateTime) values ('" +
// value1 + "', '" + value2 + "', '" + value3 + "', '" + dateTime + "')";
//SqlCommand comm = new SqlCommand(sql, conn);
//comm.ExecuteReader();
//conn.Close();

//另一种方法
string sqlStr = @"Insert Into tablename(webtype,type1,examtype,ceshitype,vip,adduid,examtitle,kemuD,kemuX,sort) Values(1,31,5,0,1,1,'"+examtitle+"',"+kemuD+","+kemuX+","+sort+")";
sqlStr += ";Select @@identity";
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = sqlStr;
// cmd.ExecuteReader();
int xid = Convert.ToInt32(cmd.ExecuteScalar());
string sqlStr1 = @"update tablenameset zxksid="+xid+" where zxksid="+yid+"";
SqlCommand cmd1 = new SqlCommand(sqlStr1, conn);
cmd1.ExecuteNonQuery();
conn.Close();
}