C#操作SQLite数据库

using System;
using System.Data.SQLite;

namespace SQLiteSamples
{
    class Program
    {
        //数据库连接
        SQLiteConnection m_dbConnection;

        static void Main(string[] args)
        {
            Program p = new Program();
        }

        public Program()
        {
            createNewDatabase();
            connectToDatabase();
            createTable();
            fillTable();
            printHighscores();
        }

        //创建一个空的数据库
        void createNewDatabase()
        {
            SQLiteConnection.CreateFile("MyDatabase.sqlite");
        }

        //创建一个连接到指定数据库
        void connectToDatabase()
        {
            m_dbConnection = new SQLiteConnection("Data Source=MyDatabase.sqlite;Version=3;");
            m_dbConnection.Open();
        }

        //在指定数据库中创建一个table
        void createTable()
        {
            string sql = "create table highscores (name varchar(20), score int)";
            SQLiteCommand command = new SQLiteCommand(sql, m_dbConnection);
            command.ExecuteNonQuery();
        }

        //插入一些数据
        void fillTable()
        {
            string sql = "insert into highscores (name, score) values ('Me', 3000)";
            SQLiteCommand command = new SQLiteCommand(sql, m_dbConnection);
            command.ExecuteNonQuery();

            sql = "insert into highscores (name, score) values ('Myself', 6000)";
            command = new SQLiteCommand(sql, m_dbConnection);
            command.ExecuteNonQuery();

            sql = "insert into highscores (name, score) values ('And I', 9001)";
            command = new SQLiteCommand(sql, m_dbConnection);
            command.ExecuteNonQuery();
        }

        //使用sql查询语句，并显示结果
        void printHighscores()
        {
            string sql = "select * from highscores order by score desc";
            SQLiteCommand command = new SQLiteCommand(sql, m_dbConnection);
            SQLiteDataReader reader = command.ExecuteReader();
            while (reader.Read())
                Console.WriteLine("Name: " + reader["name"] + "	Score: " + reader["score"]);
            Console.ReadLine();
        }
    }
}

using System;
using System.Data;
using System.Text.RegularExpressions;
using System.Xml;
using System.IO;
using System.Collections;
using System.Data.SQLite;

namespace DBUtility.SQLite
{
    /// <summary>
    /// SQLiteHelper is a utility class similar to "SQLHelper" in MS
    /// Data Access Application Block and follows similar pattern.
    /// </summary>
    public class SQLiteHelper
    {
        /// <summary>
        /// Creates a new <see cref="SQLiteHelper"/> instance. The ctor is marked private since all members are static.
        /// </summary>
        private SQLiteHelper()
        {
        }
        /// <summary>
        /// Creates the command.
        /// </summary>
        /// <param name="connection">Connection.</param>
        /// <param name="commandText">Command text.</param>
        /// <param name="commandParameters">Command parameters.</param>
        /// <returns>SQLite Command</returns>
        public static SQLiteCommand CreateCommand(SQLiteConnection connection, string commandText, params SQLiteParameter[] commandParameters)
        {
            SQLiteCommand cmd = new SQLiteCommand(commandText, connection);
            if (commandParameters.Length > 0)
            {
                foreach (SQLiteParameter parm in commandParameters)
                    cmd.Parameters.Add(parm);
            }
            return cmd;
        }

        /// <summary>
        /// Creates the command.
        /// </summary>
        /// <param name="connectionString">Connection string.</param>
        /// <param name="commandText">Command text.</param>
        /// <param name="commandParameters">Command parameters.</param>
        /// <returns>SQLite Command</returns>
        public static SQLiteCommand CreateCommand(string connectionString, string commandText, params SQLiteParameter[] commandParameters)
        {
            SQLiteConnection cn = new SQLiteConnection(connectionString);

            SQLiteCommand cmd = new SQLiteCommand(commandText, cn);

            if (commandParameters.Length > 0)
            {
                foreach (SQLiteParameter parm in commandParameters)
                    cmd.Parameters.Add(parm);
            }
            return cmd;
        }
        /// <summary>
        /// Creates the parameter.
        /// </summary>
        /// <param name="parameterName">Name of the parameter.</param>
        /// <param name="parameterType">Parameter type.</param>
        /// <param name="parameterValue">Parameter value.</param>
        /// <returns>SQLiteParameter</returns>
        public static SQLiteParameter CreateParameter(string parameterName, System.Data.DbType parameterType, object parameterValue)
        {
            SQLiteParameter parameter = new SQLiteParameter();
            parameter.DbType = parameterType;
            parameter.ParameterName = parameterName;
            parameter.Value = parameterValue;
            return parameter;
        }

        /// <summary>
        /// Shortcut method to execute dataset from SQL Statement and object[] arrray of parameter values
        /// </summary>
        /// <param name="connectionString">SQLite Connection string</param>
        /// <param name="commandText">SQL Statement with embedded "@param" style parameter names</param>
        /// <param name="paramList">object[] array of parameter values</param>
        /// <returns></returns>
        public static DataSet ExecuteDataSet(string connectionString, string commandText, object[] paramList)
        {
            SQLiteConnection cn = new SQLiteConnection(connectionString);
            SQLiteCommand cmd = cn.CreateCommand();


            cmd.CommandText = commandText;
            if (paramList != null)
            {
                AttachParameters(cmd,commandText, paramList);
            }
            DataSet ds = new DataSet();
            if (cn.State == ConnectionState.Closed)
                cn.Open();
            SQLiteDataAdapter da = new SQLiteDataAdapter(cmd);
            da.Fill(ds);
            da.Dispose();
            cmd.Dispose();
            cn.Close();
            return ds;
        }
        /// <summary>
        /// Shortcut method to execute dataset from SQL Statement and object[] arrray of  parameter values
        /// </summary>
        /// <param name="cn">Connection.</param>
        /// <param name="commandText">Command text.</param>
        /// <param name="paramList">Param list.</param>
        /// <returns></returns>
        public static DataSet ExecuteDataSet(SQLiteConnection cn, string commandText, object[] paramList)
        {

            SQLiteCommand cmd = cn.CreateCommand();


            cmd.CommandText = commandText;
            if (paramList != null)
            {
                AttachParameters(cmd,commandText, paramList);
            }
            DataSet ds = new DataSet();
            if (cn.State == ConnectionState.Closed)
                cn.Open();
            SQLiteDataAdapter da = new SQLiteDataAdapter(cmd);
            da.Fill(ds);
            da.Dispose();
            cmd.Dispose();
            cn.Close();
            return ds;
        }
        /// <summary>
        /// Executes the dataset from a populated Command object.
        /// </summary>
        /// <param name="cmd">Fully populated SQLiteCommand</param>
        /// <returns>DataSet</returns>
        public static DataSet ExecuteDataset(SQLiteCommand cmd)
        {
            if (cmd.Connection.State == ConnectionState.Closed)
                cmd.Connection.Open();
            DataSet ds = new DataSet();
            SQLiteDataAdapter da = new SQLiteDataAdapter(cmd);
            da.Fill(ds);
            da.Dispose();
            cmd.Connection.Close();
            cmd.Dispose();
            return ds;
        }

        /// <summary>
        /// Executes the dataset in a SQLite Transaction
        /// </summary>
        /// <param name="transaction">SQLiteTransaction. Transaction consists of Connection, Transaction,  /// and Command, all of which must be created prior to making this method call. </param>
        /// <param name="commandText">Command text.</param>
        /// <param name="commandParameters">Sqlite Command parameters.</param>
        /// <returns>DataSet</returns>
        /// <remarks>user must examine Transaction Object and handle transaction.connection .Close, etc.</remarks>
        public static DataSet ExecuteDataset(SQLiteTransaction transaction, string commandText, params SQLiteParameter[] commandParameters)
        {

            if (transaction == null) throw new ArgumentNullException("transaction");
            if (transaction != null && transaction.Connection == null) throw new ArgumentException("The transaction was rolled back or committed, please provide an open transaction.", "transaction");
            IDbCommand cmd = transaction.Connection.CreateCommand();
            cmd.CommandText = commandText;
            foreach (SQLiteParameter parm in commandParameters)
            {
                cmd.Parameters.Add(parm);
            }
            if (transaction.Connection.State == ConnectionState.Closed)
                transaction.Connection.Open();
            DataSet ds = ExecuteDataset((SQLiteCommand)cmd);
            return ds;
        }

        /// <summary>
        /// Executes the dataset with Transaction and object array of parameter values.
        /// </summary>
        /// <param name="transaction">SQLiteTransaction. Transaction consists of Connection, Transaction,    /// and Command, all of which must be created prior to making this method call. </param>
        /// <param name="commandText">Command text.</param>
        /// <param name="commandParameters">object[] array of parameter values.</param>
        /// <returns>DataSet</returns>
        /// <remarks>user must examine Transaction Object and handle transaction.connection .Close, etc.</remarks>
        public static DataSet ExecuteDataset(SQLiteTransaction transaction, string commandText, object[] commandParameters)
        {

            if (transaction == null) throw new ArgumentNullException("transaction");
            if (transaction != null && transaction.Connection == null) throw new ArgumentException("The transaction was rolled back or committed,                                                          please provide an open transaction.", "transaction");
            IDbCommand cmd = transaction.Connection.CreateCommand();
            cmd.CommandText = commandText;
            AttachParameters((SQLiteCommand)cmd,cmd.CommandText, commandParameters);
            if (transaction.Connection.State == ConnectionState.Closed)
                transaction.Connection.Open();

            DataSet ds = ExecuteDataset((SQLiteCommand)cmd);
            return ds;
        }

        #region UpdateDataset
        /// <summary>
        /// Executes the respective command for each inserted, updated, or deleted row in the DataSet.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  UpdateDataset(conn, insertCommand, deleteCommand, updateCommand, dataSet, "Order");
        /// </remarks>
        /// <param name="insertCommand">A valid SQL statement  to insert new records into the data source</param>
        /// <param name="deleteCommand">A valid SQL statement to delete records from the data source</param>
        /// <param name="updateCommand">A valid SQL statement used to update records in the data source</param>
        /// <param name="dataSet">The DataSet used to update the data source</param>
        /// <param name="tableName">The DataTable used to update the data source.</param>
        public static void UpdateDataset(SQLiteCommand insertCommand, SQLiteCommand deleteCommand, SQLiteCommand updateCommand, DataSet dataSet, string tableName)
        {
            if (insertCommand == null) throw new ArgumentNullException("insertCommand");
            if (deleteCommand == null) throw new ArgumentNullException("deleteCommand");
            if (updateCommand == null) throw new ArgumentNullException("updateCommand");
            if (tableName == null || tableName.Length == 0) throw new ArgumentNullException("tableName");

            // Create a SQLiteDataAdapter, and dispose of it after we are done
            using (SQLiteDataAdapter dataAdapter = new SQLiteDataAdapter())
            {
                // Set the data adapter commands
                dataAdapter.UpdateCommand = updateCommand;
                dataAdapter.InsertCommand = insertCommand;
                dataAdapter.DeleteCommand = deleteCommand;

                // Update the dataset changes in the data source
                dataAdapter.Update(dataSet, tableName);

                // Commit all the changes made to the DataSet
                dataSet.AcceptChanges();
            }
        }
        #endregion




        /// <summary>
        /// ShortCut method to return IDataReader
        /// NOTE: You should explicitly close the Command.connection you passed in as
        /// well as call Dispose on the Command  after reader is closed.
        /// We do this because IDataReader has no underlying Connection Property.
        /// </summary>
        /// <param name="cmd">SQLiteCommand Object</param>
        /// <param name="commandText">SQL Statement with optional embedded "@param" style parameters</param>
        /// <param name="paramList">object[] array of parameter values</param>
        /// <returns>IDataReader</returns>
        public static IDataReader ExecuteReader(SQLiteCommand cmd, string commandText, object[] paramList)
        {
            if (cmd.Connection == null)
                throw new ArgumentException("Command must have live connection attached.", "cmd");
            cmd.CommandText = commandText;
            AttachParameters(cmd,commandText, paramList);
            if (cmd.Connection.State == ConnectionState.Closed)
                cmd.Connection.Open();
            IDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            return rdr;
        }

        /// <summary>
        /// Shortcut to ExecuteNonQuery with SqlStatement and object[] param values
        /// </summary>
        /// <param name="connectionString">SQLite Connection String</param>
        /// <param name="commandText">Sql Statement with embedded "@param" style parameters</param>
        /// <param name="paramList">object[] array of parameter values</param>
        /// <returns></returns>
        public static int ExecuteNonQuery(string connectionString, string commandText, params object[] paramList)
        {
            SQLiteConnection cn = new SQLiteConnection(connectionString);
            SQLiteCommand cmd = cn.CreateCommand();
            cmd.CommandText = commandText;
            AttachParameters(cmd,commandText, paramList);
            if (cn.State == ConnectionState.Closed)
                cn.Open();
            int result = cmd.ExecuteNonQuery();
            cmd.Dispose();
            cn.Close();

            return result;
        }



        public static int ExecuteNonQuery(SQLiteConnection cn, string commandText, params  object[] paramList)
        {

            SQLiteCommand cmd = cn.CreateCommand();
            cmd.CommandText = commandText;
            AttachParameters(cmd,commandText, paramList);
            if (cn.State == ConnectionState.Closed)
                cn.Open();
            int result = cmd.ExecuteNonQuery();
            cmd.Dispose();
            cn.Close();

            return result;
        }

        /// <summary>
        /// Executes  non-query sql Statment with Transaction
        /// </summary>
        /// <param name="transaction">SQLiteTransaction. Transaction consists of Connection, Transaction,   /// and Command, all of which must be created prior to making this method call. </param>
        /// <param name="commandText">Command text.</param>
        /// <param name="paramList">Param list.</param>
        /// <returns>Integer</returns>
        /// <remarks>user must examine Transaction Object and handle transaction.connection .Close, etc.</remarks>
        public static int ExecuteNonQuery(SQLiteTransaction transaction, string commandText, params  object[] paramList)
        {
            if (transaction == null) throw new ArgumentNullException("transaction");
            if (transaction != null && transaction.Connection == null) throw new ArgumentException("The transaction was rolled back or committed,                                                        please provide an open transaction.", "transaction");
            IDbCommand cmd = transaction.Connection.CreateCommand();
            cmd.CommandText = commandText;
            AttachParameters((SQLiteCommand)cmd,cmd.CommandText, paramList);
            if (transaction.Connection.State == ConnectionState.Closed)
                transaction.Connection.Open();
            int result = cmd.ExecuteNonQuery();
            cmd.Dispose();
            return result;
        }


        /// <summary>
        /// Executes the non query.
        /// </summary>
        /// <param name="cmd">CMD.</param>
        /// <returns></returns>
        public static int ExecuteNonQuery(IDbCommand cmd)
        {
            if (cmd.Connection.State == ConnectionState.Closed)
                cmd.Connection.Open();
            int result = cmd.ExecuteNonQuery();
            cmd.Connection.Close();
            cmd.Dispose();
            return result;
        }

        /// <summary>
        /// Shortcut to ExecuteScalar with Sql Statement embedded params and object[] param values
        /// </summary>
        /// <param name="connectionString">SQLite Connection String</param>
        /// <param name="commandText">SQL statment with embedded "@param" style parameters</param>
        /// <param name="paramList">object[] array of param values</param>
        /// <returns></returns>
        public static object ExecuteScalar(string connectionString, string commandText, params  object[] paramList)
        {
            SQLiteConnection cn = new SQLiteConnection(connectionString);
            SQLiteCommand cmd = cn.CreateCommand();
            cmd.CommandText = commandText;
            AttachParameters(cmd,commandText, paramList);
            if (cn.State == ConnectionState.Closed)
                cn.Open();
            object result = cmd.ExecuteScalar();
            cmd.Dispose();
            cn.Close();

            return result;
        }

        /// <summary>
        /// Execute XmlReader with complete Command
        /// </summary>
        /// <param name="command">SQLite Command</param>
        /// <returns>XmlReader</returns>
        public static XmlReader ExecuteXmlReader(IDbCommand command)
        { // open the connection if necessary, but make sure we 
            // know to close it when we�re done.
            if (command.Connection.State != ConnectionState.Open)
            {
                command.Connection.Open();
            }

            // get a data adapter  
            SQLiteDataAdapter da = new SQLiteDataAdapter((SQLiteCommand)command);
            DataSet ds = new DataSet();
            // fill the data set, and return the schema information
            da.MissingSchemaAction = MissingSchemaAction.AddWithKey;
            da.Fill(ds);
            // convert our dataset to XML
            StringReader stream = new StringReader(ds.GetXml());
            command.Connection.Close();
            // convert our stream of text to an XmlReader
            return new XmlTextReader(stream);
        }



        /// <summary>
        /// Parses parameter names from SQL Statement, assigns values from object array ,   /// and returns fully populated ParameterCollection.
        /// </summary>
        /// <param name="commandText">Sql Statement with "@param" style embedded parameters</param>
        /// <param name="paramList">object[] array of parameter values</param>
        /// <returns>SQLiteParameterCollection</returns>
        /// <remarks>Status experimental. Regex appears to be handling most issues. Note that parameter object array must be in same ///order as parameter names appear in SQL statement.</remarks>
        private static SQLiteParameterCollection AttachParameters(SQLiteCommand cmd, string commandText, params  object[] paramList)
        {
            if (paramList == null || paramList.Length == 0) return null;

            SQLiteParameterCollection coll = cmd.Parameters;
            string parmString = commandText.Substring(commandText.IndexOf("@"));
            // pre-process the string so always at least 1 space after a comma.
            parmString = parmString.Replace(",", " ,");
            // get the named parameters into a match collection
            string pattern = @"(@)S*(.*?)";
            Regex ex = new Regex(pattern, RegexOptions.IgnoreCase);
            MatchCollection mc = ex.Matches(parmString);
            string[] paramNames = new string[mc.Count];
            int i = 0;
            foreach (Match m in mc)
            {
                paramNames[i] = m.Value;
                i++;
            }

            // now let's type the parameters
            int j = 0;
            Type t = null;
            foreach (object o in paramList)
            {
                t = o.GetType();

                SQLiteParameter parm = new SQLiteParameter();
                switch (t.ToString())
                {

                    case ("DBNull"):
                    case ("Char"):
                    case ("SByte"):
                    case ("UInt16"):
                    case ("UInt32"):
                    case ("UInt64"):
                        throw new SystemException("Invalid data type");


                    case ("System.String"):
                        parm.DbType = DbType.String;
                        parm.ParameterName = paramNames[j];
                        parm.Value = (string)paramList[j];
                        coll.Add(parm);
                        break;

                    case ("System.Byte[]"):
                        parm.DbType = DbType.Binary;
                        parm.ParameterName = paramNames[j];
                        parm.Value = (byte[])paramList[j];
                        coll.Add(parm);
                        break;

                    case ("System.Int32"):
                        parm.DbType = DbType.Int32;
                        parm.ParameterName = paramNames[j];
                        parm.Value = (int)paramList[j];
                        coll.Add(parm);
                        break;

                    case ("System.Boolean"):
                        parm.DbType = DbType.Boolean;
                        parm.ParameterName = paramNames[j];
                        parm.Value = (bool)paramList[j];
                        coll.Add(parm);
                        break;

                    case ("System.DateTime"):
                        parm.DbType = DbType.DateTime;
                        parm.ParameterName = paramNames[j];
                        parm.Value = Convert.ToDateTime(paramList[j]);
                        coll.Add(parm);
                        break;

                    case ("System.Double"):
                        parm.DbType = DbType.Double;
                        parm.ParameterName = paramNames[j];
                        parm.Value = Convert.ToDouble(paramList[j]);
                        coll.Add(parm);
                        break;

                    case ("System.Decimal"):
                        parm.DbType = DbType.Decimal;
                        parm.ParameterName = paramNames[j];
                        parm.Value = Convert.ToDecimal(paramList[j]);
                        break;

                    case ("System.Guid"):
                        parm.DbType = DbType.Guid;
                        parm.ParameterName = paramNames[j];
                        parm.Value = (System.Guid)(paramList[j]);
                        break;

                    case ("System.Object"):

                        parm.DbType = DbType.Object;
                        parm.ParameterName = paramNames[j];
                        parm.Value = paramList[j];
                        coll.Add(parm);
                        break;

                    default:
                        throw new SystemException("Value is of unknown data type");

                } // end switch

                j++;
            }
            return coll;
        }

        /// <summary>
        /// Executes non query typed params from a DataRow
        /// </summary>
        /// <param name="command">Command.</param>
        /// <param name="dataRow">Data row.</param>
        /// <returns>Integer result code</returns>
        public static int ExecuteNonQueryTypedParams(IDbCommand command, DataRow dataRow)
        {
            int retVal = 0;

            // If the row has values, the store procedure parameters must be initialized
            if (dataRow != null && dataRow.ItemArray.Length > 0)
            {
                // Set the parameters values
                AssignParameterValues(command.Parameters, dataRow);

                retVal = ExecuteNonQuery(command);
            }
            else
            {
                retVal = ExecuteNonQuery(command);
            }

            return retVal;
        }

        /// <summary>
        /// This method assigns dataRow column values to an IDataParameterCollection
        /// </summary>
        /// <param name="commandParameters">The IDataParameterCollection to be assigned values</param>
        /// <param name="dataRow">The dataRow used to hold the command's parameter values</param>
        /// <exception cref="System.InvalidOperationException">Thrown if any of the parameter names are invalid.</exception>
        protected internal static void AssignParameterValues(IDataParameterCollection commandParameters, DataRow dataRow)
        {
            if (commandParameters == null || dataRow == null)
            {
                // Do nothing if we get no data
                return;
            }

            DataColumnCollection columns = dataRow.Table.Columns;

            int i = 0;
            // Set the parameters values
            foreach (IDataParameter commandParameter in commandParameters)
            {
                // Check the parameter name
                if (commandParameter.ParameterName == null ||
                 commandParameter.ParameterName.Length <= 1)
                    throw new InvalidOperationException(string.Format(
                           "Please provide a valid parameter name on the parameter #{0},                            the ParameterName property has the following value: '{1}'.",
                     i, commandParameter.ParameterName));

                if (columns.Contains(commandParameter.ParameterName))
                    commandParameter.Value = dataRow[commandParameter.ParameterName];
                else if (columns.Contains(commandParameter.ParameterName.Substring(1)))
                    commandParameter.Value = dataRow[commandParameter.ParameterName.Substring(1)];

                i++;
            }
        }

        /// <summary>
        /// This method assigns dataRow column values to an array of IDataParameters
        /// </summary>
        /// <param name="commandParameters">Array of IDataParameters to be assigned values</param>
        /// <param name="dataRow">The dataRow used to hold the stored procedure's parameter values</param>
        /// <exception cref="System.InvalidOperationException">Thrown if any of the parameter names are invalid.</exception>
        protected void AssignParameterValues(IDataParameter[] commandParameters, DataRow dataRow)
        {
            if ((commandParameters == null) || (dataRow == null))
            {
                // Do nothing if we get no data
                return;
            }

            DataColumnCollection columns = dataRow.Table.Columns;

            int i = 0;
            // Set the parameters values
            foreach (IDataParameter commandParameter in commandParameters)
            {
                // Check the parameter name
                if (commandParameter.ParameterName == null ||
                 commandParameter.ParameterName.Length <= 1)
                    throw new InvalidOperationException(string.Format(
                     "Please provide a valid parameter name on the parameter #{0}, the ParameterName property has the following value: '{1}'.",
                     i, commandParameter.ParameterName));

                if (columns.Contains(commandParameter.ParameterName))
                    commandParameter.Value = dataRow[commandParameter.ParameterName];
                else if (columns.Contains(commandParameter.ParameterName.Substring(1)))
                    commandParameter.Value = dataRow[commandParameter.ParameterName.Substring(1)];

                i++;
            }
        }

        /// <summary>
        /// This method assigns an array of values to an array of IDataParameters
        /// </summary>
        /// <param name="commandParameters">Array of IDataParameters to be assigned values</param>
        /// <param name="parameterValues">Array of objects holding the values to be assigned</param>
        /// <exception cref="System.ArgumentException">Thrown if an incorrect number of parameters are passed.</exception>
        protected void AssignParameterValues(IDataParameter[] commandParameters, params  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 IDataParameters, assigning the values from the corresponding position in the 
            // value array
            for (int i = 0, j = commandParameters.Length, k = 0; i < j; i++)
            {
                if (commandParameters[i].Direction != ParameterDirection.ReturnValue)
                {
                    // If the current array value derives from IDataParameter, then assign its Value property
                    if (parameterValues[k] is IDataParameter)
                    {
                        IDataParameter paramInstance;
                        paramInstance = (IDataParameter)parameterValues[k];
                        if (paramInstance.Direction == ParameterDirection.ReturnValue)
                        {
                            paramInstance = (IDataParameter)parameterValues[++k];
                        }
                        if (paramInstance.Value == null)
                        {
                            commandParameters[i].Value = DBNull.Value;
                        }
                        else
                        {
                            commandParameters[i].Value = paramInstance.Value;
                        }
                    }
                    else if (parameterValues[k] == null)
                    {
                        commandParameters[i].Value = DBNull.Value;
                    }
                    else
                    {
                        commandParameters[i].Value = parameterValues[k];
                    }
                    k++;
                }
            }
        }
    }
}

引自 http://www.cnblogs.com/luxiaoxun/p/3784729.html