SQLHelper offers some common function to operate DB


using System.Configuration;
using System.Data;
using System.Data.SqlClient;

    public class SQLHelper
    {
        public SqlConnection XXX_P = new SqlConnection(ConfigurationManager.AppSettings["XXX_P"].ToString());

        public SqlConnection connALL(string connDB)
        {
            conn = new SqlConnection(ConfigurationManager.AppSettings[connDB].ToString());
            return conn;
        }

        public DataTable getDataTable(SqlConnection sqlConn, string cmdText)
        {
            if (sqlConn.State == ConnectionState.Closed)
            {
                sqlConn.Open();
            }
            SqlCommand comm = null;
            SqlDataAdapter sda = null;
            DataTable dt = new DataTable();
            try
            {
                comm = new SqlCommand(cmdText, sqlConn);
                sda = new SqlDataAdapter(comm);
                sda.Fill(dt);
                return dt;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        public DataSet GetDataSet(SqlConnection sqlConn, string cmdText)
        {
            if (sqlConn.State == ConnectionState.Closed)
            {
                sqlConn.Open();
            }

            try
            {
                SqlDataAdapter dataAdapter = new SqlDataAdapter(cmdText, sqlConn);
                DataSet dataSet = new DataSet();
                dataAdapter.Fill(dataSet);
                return dataSet;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        public bool ExecSQL(SqlConnection sqlConn, string cmdText)
        {
            if (sqlConn.State == ConnectionState.Closed)
            {
                sqlConn.Open();
            }
            bool result = false;
            using (SqlCommand sqlcommand = new SqlCommand(cmdText, sqlConn))
            {
                try
                {
                    sqlcommand.ExecuteNonQuery();
                    result = true;
                }
                catch (Exception e)
                {
                    throw new Exception(e.Message, e);
                }
                return result;
            }
        }
        public int ExeNonQuery(SqlConnection sqlConn, string cmdText)
        {
            if (sqlConn.State == ConnectionState.Closed)
            {
                sqlConn.Open();
            }
            using (SqlCommand sqlCommand = new SqlCommand(cmdText, sqlConn))
            {
                int rows = sqlCommand.ExecuteNonQuery();
                return rows;
            }
        }

        public string GetFieldValue(SqlConnection sqlConn, string cmdText)
        {
            string fieldValue = "";
            if (sqlConn.State == ConnectionState.Closed)
            {
                sqlConn.Open();
            }
            using (SqlCommand sqlCommand = new SqlCommand(cmdText, sqlConn))
            {
                try
                {
                    object bjFieldValue = sqlCommand.ExecuteScalar();
                    if (objFieldValue != null)
                    {
                        fieldValue = objFieldValue.ToString();
                    }
                }
                catch (Exception e)
                {
                    throw new Exception(e.Message, e);
                }

                return fieldValue;
            }
        }

        public void CloseConn(SqlConnection sqlConn)
        {
            if (sqlConn.State == ConnectionState.Open)
            {
                sqlConn.Close();
            }
        }
    }

app.config