如何做一个链接数据库的类

Question

 常用的一个数据库连接类 这里连接字符串是直接写在这的public static class DBHelper
    {        private static SqlConnection connection;        #region 打开 SqlService连接
        public static SqlConnection Connection
        {
            get
            {
                     string connectionString = "Data Source=192.168.1.1;Initial Catalog=PsyExamSystem;User ID=sa;Pwd=sa";
                    //string connectionString = ConfigurationManager.ConnectionStrings["connString"].ConnectionString;
                    if (connection == null)
                    {
                        connection = new SqlConnection(connectionString);
                        connection.Open();
                    }
                    else if (connection.State == System.Data.ConnectionState.Closed)
                    {
                        connection.Open();
                    }
                    else if (connection.State == System.Data.ConnectionState.Broken)
                    {
                        connection.Close();
                        connection.Open();
                    }
                    return connection;
            }
        }
        #endregion
        public static int ExecuteCommand(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = cmd.ExecuteNonQuery();
            return result;
        }        public static int ExecuteCommand(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            return cmd.ExecuteNonQuery();
        }        public static int GetScalar(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }        public static int GetScalar(CommandType ct, string safeSql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = Connection;
            cmd.CommandText = safeSql;
            cmd.CommandType = ct;
            cmd.Parameters.AddRange(values);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }        public static int GetScalar(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }        public static SqlDataReader GetReader(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }        public static SqlDataReader GetReader(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }        public static DataTable GetDataSet(string safeSql)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(safeSql, Connection);            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }        public static DataTable GetDataSet(string sql, params SqlParameter[] values)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }    }

Answer 1

sqlhelper
public class SqlDbHelper
    {
        private string connectionString;
        public string ConnectionString
        {
            set { connectionString = value; }
        }
        public SqlDbHelper() : this(ConfigurationManager.ConnectionStrings["Conn"].ConnectionString)
        {        }
        public SqlDbHelper(string connectionString)
        {
            this.connectionString = connectionString;
        }
public DataTable ExecuteDataTable(string sql, CommandType commandType, SqlParameter[] parameters)
        {
          DataTable data = new DataTable();
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand command = new SqlCommand(sql, connection))
                {
                 command.CommandType = commandType;
                    if (parameters != null)
                    {
                        foreach (SqlParameter parameter in parameters)
                        {
                            command.Parameters.Add(parameter);
                        }
                    }
                    SqlDataAdapter adapter = new SqlDataAdapter(command);
                    adapter.Fill(data);
                }
            }
            return data;
        }}
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