DBHelper数据库操作封装类

先引入命名空间

[code]using System.Data;
using System.Data.SqlClient;

然后

[code]class DBHelper
{
public static string ConnString = "server=.;database=FileDB;Integrated Security=true;";
public static SqlConnection conn = null;
private static void InitConnection()
{
if (conn == null)
conn = new SqlConnection(ConnString);
if (conn.State == ConnectionState.Broken)
{
conn.Close();
conn.Open();
}
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}

}
//获取DataReader
public static SqlDataReader GetDataReader(string str)
{
InitConnection();
SqlCommand cmd = new SqlCommand(str, conn);
return cmd.ExecuteReader(CommandBehavior.CloseConnection);
}
//查询，获取DataSet
public static DataSet GetDataSet(string sqlStr)
{
InitConnection();
DataSet ds = new DataSet();
SqlDataAdapter dap = new SqlDataAdapter(sqlStr, conn);
dap.Fill(ds);
conn.Close();
return ds;
}

//查询，获取DataTable
public static DataTable GetDataTable(string sqlStr)
{
return GetDataSet(sqlStr).Tables[0];
}
//增删改
public static int ExecuteNonQuery(string str)
{
InitConnection();
SqlCommand cmd = new SqlCommand(str, conn);
int result = cmd.ExecuteNonQuery();
conn.Close();
return result;
}
//执行集合函数
public static object ExecuteScalar(string str)
{
InitConnection();
SqlCommand cmd = new SqlCommand(str, conn);
object result = cmd.ExecuteScalar();
conn.Close();
return result;
}
}