npgsqlhelper.cs

.net数据库操作类源码.分别有ms sql server , oracle , ole db , Npg的数据

using System;
using System.Data;
using Npgsql;
using System.Collections;

namespace PCS2.DbUtility
{
    public sealed class NpgsqlHelper
    {
        private NpgsqlHelper() { }

        private static void AssignParameterValues(NpgsqlParameter[] commandParameters, object[] parameterValues)
        {
            if ((commandParameters == null) || (parameterValues == null))
            {
                //do nothing if we get no data
                return;
            }

            // we must have the same number of values as we pave parameters to put them in
            if (commandParameters.Length != parameterValues.Length)
            {
                throw new ArgumentException("Parameter count does not match Parameter Value count.");
            }

            //iterate through the NpgsqlParameters, assigning the values from the corresponding position in the 
            //value array
            for (int i = 0, j = commandParameters.Length; i < j; i++)
            {
                commandParameters[i].Value = parameterValues[i];
            }
        }

        private static void PrepareCommand(NpgsqlCommand command, NpgsqlConnection connection, NpgsqlTransaction transaction, CommandType commandType, string commandText, NpgsqlParameter[] commandParameters)
        {
            if (connection.State != ConnectionState.Open)
            {
                connection.Open();
            }
            command.Connection = connection;
            command.CommandText = commandText;

            if (transaction != null)
            {
                command.Transaction = transaction;
            }
            command.CommandType = commandType;

            if (commandParameters != null)
            {
                AttachParameters(command, commandParameters);
            }

            return;
        }

        private static void AttachParameters(NpgsqlCommand command, NpgsqlParameter[] commandParameters)
        {
            foreach (NpgsqlParameter p in commandParameters)
            {
                //check for derived output value with no value assigned
                if ((p.Direction == ParameterDirection.InputOutput) && (p.Value == null))
                {
                    p.Value = DBNull.Value;
                }

                command.Parameters.Add(p);
            }
        }

        #region ExecuteReader
        public static NpgsqlDataReader ExecuteReader(string connectionString, CommandType commandType, string commandText, params NpgsqlParameter[] commandParameters)
        {
            //create & open an NpgsqlConnection
            NpgsqlConnection cn = new NpgsqlConnection(connectionString);

            try
            {
                cn.Open();
                //call the private overload that takes an internally owned connection in place of the connection string
                return ExecuteReader(cn, commandType, commandText, commandParameters);
            }
            catch
            {
                //if we fail to return the NpgsqlDbDataReader, we neeed to close the connection ourselves
                cn.Close();
                throw;
            }
        }

        public static NpgsqlDataReader ExecuteReader(NpgsqlConnection connection, CommandType commandType, string commandText, params NpgsqlParameter[] commandParameters)
        {
            //create & open an NpgsqlConnection
            NpgsqlCommand cmd = new NpgsqlCommand();
            PrepareCommand(cmd, connection, null, commandType, commandText, commandParameters);

            try
            {
                //call the private overload that takes an internally owned connection in place of the connection string
                return cmd.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch
            {
                //if we fail to return the NpgsqlDbDataReader, we neeed to close the connection ourselves
                throw;
            }
        }

        public static NpgsqlDataReader ExecuteReader(NpgsqlConnection connection, CommandType commandType, string commandText)
        {
            return ExecuteReader(connection, commandType, commandText, (NpgsqlParameter[])null);
        }

        public static NpgsqlDataReader ExecuteReader(string connectionString, CommandType commandType, string commandText)
        {
            return ExecuteReader(connectionString, commandType, commandText, (NpgsqlParameter[])null);
        }
        #endregion

        #region ExecuteNonQuery

        /// <summary>
        /// Execute an NpgsqlCommand (that returns no resultset and takes no parameters) against the database specified in 
        /// the connection string. 
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders");
        /// </remarks>
        /// <param name="connectionString">a valid connection string for an NpgsqlConnection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText)
        {
            //pass through the call providing null for the set of NpgsqlParameters
            return ExecuteNonQuery(connectionString, commandType, commandText, (NpgsqlParameter[])null);
        }

        /// <summary>
        /// Execute an NpgsqlCommand (that returns no resultset) against the database specified in the connection string 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new NpgsqlParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connectionString">a valid connection string for a NpgsqlConnection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
        /// <param name="commandParameters">an array of NpgsqlParameters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText, params NpgsqlParameter[] commandParameters)
        {
            //create & open an NpgsqlConnection, and dispose of it after we are done.
            using (NpgsqlConnection cn = new NpgsqlConnection(connectionString))
            {
                cn.Open();

                //call the overload that takes a connection in place of the connection string
                return ExecuteNonQuery(cn, commandType, commandText, commandParameters);
            }
        }

        /// <summary>
        /// Execute a stored procedure via an NpgsqlCommand (that returns no resultset) against the database specified in 
        /// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 
        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
        /// </summary>
        /// <remarks>
        /// This method provides no access to output parameters or the stored procedure's return value parameter.
        /// 
        /// e.g.:  
        ///  int result = ExecuteNonQuery(connString, "PublishOrders", 24, 36);
        /// </remarks>
        /// <param name="connectionString">a valid connection string for a NpgsqlConnection</param>
        /// <param name="spName">the name of the stored prcedure</param>
        /// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(string connectionString, string spName, params object[] parameterValues)
        {
            //if we got parameter values, we need to figure out where they go
            if ((parameterValues != null) && (parameterValues.Length > 0))
            {
                //pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
                NpgsqlParameter[] commandParameters = NpgsqlHelperParameterCache.GetSpParameterSet(connectionString, spName);

                //assign the provided values to these parameters based on parameter order
                AssignParameterValues(commandParameters, parameterValues);

                //call the overload that takes an array of NpgsqlParameters
                return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName, commandParameters);
            }
            //otherwise we can just call the SP without params
            else
            {
                return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName);
            }
        }

        /// <summary>
        /// Execute an NpgsqlDbCommand (that returns no resultset and takes no parameters) against the provided NpgsqlConnection. 
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders");
        /// </remarks>
        /// <param name="connection">a valid NpgsqlConnection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or PL/SQL command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(NpgsqlConnection connection, CommandType commandType, string commandText)
        {
            //pass through the call providing null for the set of NpgsqlParameters
            return ExecuteNonQuery(connection, commandType, commandText, (NpgsqlParameter[])null);
        }

        /// <summary>
        /// Execute an NpgsqlCommand (that returns no resultset) against the specified NpgsqlConnection 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new NpgsqlParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connection">a valid NpgsqlConnection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or PL/SQL command</param>  
        /// <param name="commandParameters">an array of NpgsqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(NpgsqlConnection connection, CommandType commandType, string commandText, params NpgsqlParameter[] commandParameters)
        {
            //create a command and prepare it for execution
            NpgsqlCommand cmd = new NpgsqlCommand();
            PrepareCommand(cmd, connection, (NpgsqlTransaction)null, commandType, commandText, commandParameters);

            //finally, execute the command.
            return cmd.ExecuteNonQuery();
        }

        /// <summary>
        /// Execute a stored procedure via an NpgsqlCommand (that returns no resultset) against the specified NpgsqlConnection 
        /// using the provided parameter values.  This method will query the database to discover the parameters for the 
        /// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
        /// </summary>
        /// <remarks>