//===============================================================================
// This file is based on the Microsoft Data Access Application Block for .NET
// For more information please go to 
// http://msdn.microsoft.com/library/en-us/dnbda/html/daab-rm.asp
//===============================================================================

using System;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Data.Odbc;
using System.Collections;


/// <summary>
/// The SqlHelper class is intended to encapsulate high performance, 
/// scalable best practices for common uses of SqlClient.
/// </summary>
public abstract class SqlHelper {

	//Database connection strings
	public static readonly string ConnectionString = "";		
	
	// Hashtable to store cached parameters
	private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());

	/// <summary>
	/// Execute a SqlCommand (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 SqlParameter("@prodid", 24));
	/// </remarks>
	/// <param name="connectionString">a valid connection string for a SqlConnection</param>
	/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
	/// <param name="commandText">the stored procedure name or T-SQL command</param>
	/// <param name="commandParameters">an array of SqlParamters 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 cmdType, string cmdText, params SqlParameter[] commandParameters) {

		SqlCommand cmd = new SqlCommand();

		using (SqlConnection conn = new SqlConnection(connectionString)) {
			PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
			int val = cmd.ExecuteNonQuery();
			cmd.Parameters.Clear();
			return val;
		}
	}

	/// <summary>
	/// Execute a SqlCommand (that returns no resultset) against an existing database connection 
	/// using the provided parameters.
	/// </summary>
	/// <remarks>
	/// e.g.:  
	///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
	/// </remarks>
	/// <param name="conn">an existing database connection</param>
	/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
	/// <param name="commandText">the stored procedure name or T-SQL command</param>
	/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
	/// <returns>an int representing the number of rows affected by the command</returns>
	public static int ExecuteNonQuery(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {

		SqlCommand cmd = new SqlCommand();

		PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
		int val = cmd.ExecuteNonQuery();
		cmd.Parameters.Clear();
		return val;
	}

	/// <summary>
	/// Execute a SqlCommand (that returns no resultset) using an existing SQL Transaction 
	/// using the provided parameters.
	/// </summary>
	/// <remarks>
	/// e.g.:  
	///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
	/// </remarks>
	/// <param name="trans">an existing sql transaction</param>
	/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
	/// <param name="commandText">the stored procedure name or T-SQL command</param>
	/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
	/// <returns>an int representing the number of rows affected by the command</returns>
	public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {
		SqlCommand cmd = new SqlCommand();
		PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
		int val = cmd.ExecuteNonQuery();
		cmd.Parameters.Clear();
		return val;
	}

	/// <summary>
	/// Execute a SqlCommand that returns a resultset against the database specified in the connection string 
	/// using the provided parameters.
	/// </summary>
	/// <remarks>
	/// e.g.:  
	///  SqlDataReader r = ExecuteReader(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
	/// </remarks>
	/// <param name="connectionString">a valid connection string for a SqlConnection</param>
	/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
	/// <param name="commandText">the stored procedure name or T-SQL command</param>
	/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
	/// <returns>A SqlDataReader containing the results</returns>
	public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {
		SqlCommand cmd = new SqlCommand();
		SqlConnection conn = new SqlConnection(connectionString);

		// we use a try/catch here because if the method throws an exception we want to 
		// close the connection throw code, because no datareader will exist, hence the 
		// commandBehaviour.CloseConnection will not work
		try {
			PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
			SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
			cmd.Parameters.Clear();
			return rdr;
		}
		catch {
			conn.Close();
			throw;
		}
	}

    /// <summary>
    /// Ö´ÐвéѯÓï¾ä£¬·µ»ØDataSet
    /// </summary>
    /// <param name="SQLString">²éѯÓï¾ä</param>
    /// <returns>DataSet</returns>
    public static DataSet Query(string connectionString, string SQLString)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            DataSet ds = new DataSet();
            try
            {
                connection.Open();
                SqlDataAdapter command = new SqlDataAdapter(SQLString, connection);
                command.Fill(ds, "ds");
            }
            catch (System.Data.SqlClient.SqlException ex)
            {
                throw new Exception(ex.Message);
            }
            return ds;
        }
    }

    /// <summary>
    /// Execute a SqlCommand that returns the first column of the first record against the database specified in the connection string 
    /// using the provided parameters.
    /// </summary>
    /// <remarks>
    /// e.g.:  
    ///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
    /// </remarks>
    /// <param name="connectionString">a valid connection string for a SqlConnection</param>
    /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
    /// <param name="commandText">the stored procedure name or T-SQL command</param>
    /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
    /// <returns>An object that should be converted to the expected type using Convert.To{Type}</returns>
    public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {
		SqlCommand cmd = new SqlCommand();

		using (SqlConnection connection = new SqlConnection(connectionString)) {
			PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
			object val = cmd.ExecuteScalar();
			cmd.Parameters.Clear();
			return val;
		}
	}

	/// <summary>
	/// Execute a SqlCommand that returns the first column of the first record against an existing database connection 
	/// using the provided parameters.
	/// </summary>
	/// <remarks>
	/// e.g.:  
	///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
	/// </remarks>
	/// <param name="conn">an existing database connection</param>
	/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
	/// <param name="commandText">the stored procedure name or T-SQL command</param>
	/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
	/// <returns>An object that should be converted to the expected type using Convert.To{Type}</returns>
	public static object ExecuteScalar(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {

		SqlCommand cmd = new SqlCommand();

		PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
		object val = cmd.ExecuteScalar();
		cmd.Parameters.Clear();
		return val;
	}

	/// <summary>
	/// add parameter array to the cache
	/// </summary>
	/// <param name="cacheKey">Key to the parameter cache</param>
	/// <param name="cmdParms">an array of SqlParamters to be cached</param>
	public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters) {
		parmCache[cacheKey] = commandParameters;
	}

	/// <summary>
	/// Retrieve cached parameters
	/// </summary>
	/// <param name="cacheKey">key used to lookup parameters</param>
	/// <returns>Cached SqlParamters array</returns>
	public static SqlParameter[] GetCachedParameters(string cacheKey) {
		SqlParameter[] cachedParms = (SqlParameter[])parmCache[cacheKey];

		if (cachedParms == null)
			return null;

		SqlParameter[] clonedParms = new SqlParameter[cachedParms.Length];

		for (int i = 0, j = cachedParms.Length; i < j; i++)
			clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();

		return clonedParms;
	}

	/// <summary>
	/// Prepare a command for execution
	/// </summary>
	/// <param name="cmd">SqlCommand object</param>
	/// <param name="conn">SqlConnection object</param>
	/// <param name="trans">SqlTransaction object</param>
	/// <param name="cmdType">Cmd type e.g. stored procedure or text</param>
	/// <param name="cmdText">Command text, e.g. Select * from Products</param>
	/// <param name="cmdParms">SqlParameters to use in the command</param>
	private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms) {

		if (conn.State != ConnectionState.Open)
			conn.Open();

		cmd.Connection = conn;
		cmd.CommandText = cmdText;

		if (trans != null)
			cmd.Transaction = trans;

		cmd.CommandType = cmdType;

		if (cmdParms != null) {
			foreach (SqlParameter parm in cmdParms)
				cmd.Parameters.Add(parm);
		}
	}
}