SqlHelper 数据库操作类2

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

namespace lsb.DBUtility
{
    /// <summary>
    /// SQL Server 数据库操作类
    /// </summary>
    public class SqlHelper
    {
        private static string connectionString = "Data Source=.;Initial Catalog=FBMS;Integrated Security=True";

        /// <summary>
        /// 执行查询, 返回单个值
        /// </summary>
        public static object ExecuteScalar(string sql)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand(sql, conn))
                {
                    try
                    {
                        conn.Open();
                        return cmd.ExecuteScalar();
                    }
                    catch
                    {
                        throw;
                    }
                }
            }
        }

        /// <summary>
        /// 执行带参数查询, 返回单个值
        /// </summary>
        public static object ExecuteScalar(string sql, SqlParameter[] cmdParms)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    try
                    {
                        PrepareCommand(cmd, conn, null, sql, cmdParms);
                        object obj = cmd.ExecuteScalar();
                        cmd.Parameters.Clear();
                        return obj;
                    }
                    catch
                    {
                        throw;
                    }
                }
            }
        }

        /// <summary>
        /// 执行查询, 返回多个值
        /// </summary>
        public static SqlDataReader ExecuteReader(string sql)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand(sql, conn))
                {
                    try
                    {
                        conn.Open();
                        return cmd.ExecuteReader();
                    }
                    catch
                    {
                        throw;
                    }
                }
            }
        }

        /// <summary>
        /// 执行带参数查询, 返回多个值
        /// </summary>
        public static SqlDataReader ExecuteReader(string sql, SqlParameter[] cmdParms)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    try
                    {
                        PrepareCommand(cmd, conn, null, sql, cmdParms);
                        SqlDataReader sdr = cmd.ExecuteReader();
                        cmd.Parameters.Clear();
                        return sdr;
                    }
                    catch
                    {
                        throw;
                    }
                }
            }
        }

        /// <summary>
        /// 执行非查询, 返回影响行数
        /// </summary>
        public static int ExceuteNonQuery(string sql, params SqlParameter[] cmdParms)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    try
                    {
                        PrepareCommand(cmd, conn, null, sql, cmdParms);
                        int rows = cmd.ExecuteNonQuery();
                        cmd.Parameters.Clear();
                        return rows;
                    }
                    catch
                    {
                        throw;
                    }
                }
            }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="cmd"></param>
        /// <param name="conn"></param>
        /// <param name="trans"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, string cmdText, SqlParameter[] cmdParms)
        {
            if ((conn.State == ConnectionState.Broken) || (conn.State == ConnectionState.Closed))
            {
                conn.Open();
            }

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

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

            cmd.CommandType = CommandType.Text;

            if (cmdParms != null)
            {
                foreach (SqlParameter parm in cmdParms)
                {
                    if ((parm.Direction == ParameterDirection.InputOutput || parm.Direction == ParameterDirection.Input) && (parm.Value == null))
                    {
                        parm.Value = DBNull.Value;
                    }
                    cmd.Parameters.Add(parm);
                }
            }
        }
    }
}