using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;

namespace SQLHelper
{
    public static class SqlHelper
    {
        //从配置文件中获取连接字符串   readonly修饰的变量只能在初始化或构造函数中赋值；其他地方只能读取
        //private static readonly string constr = ConfigurationManager.ConnectionStrings["OperationHistory"].ConnectionString;
        private static readonly string constr = "Data Source=/*主机名或者目标主机IP地址*/;Initial Catalog=/*数据库名*/;User=sa;PassWord=123";

        /// <summary>
        /// 增、删、改的方法[ExecuteNonQuery] 返回所影响的行数，执行其他
        /// </summary>
        /// <param name="sql">Sql命令</param>
        /// <param name="cmdtype">SQL语句（CommandType.Text）或者存储过程(CommandType.StoredProcedure)</param>
        /// <param name="pms"></param>
        /// <returns></returns>
        public static int ExecuteNonQuery(string sql, CommandType cmdtype, params SqlParameter[] pms)
        {
            ;
            try
            {
                using (SqlConnection con = new SqlConnection(constr))
                {
                    using (SqlCommand cmd = new SqlCommand(sql, con))
                    {
                        //存储过程或者Sql语句
                        cmd.CommandType = cmdtype;
                        if (pms != null)
                        {
                            cmd.Parameters.AddRange(pms);
                        }

                        con.Open();
                        i = cmd.ExecuteNonQuery();
                    }
                }
            }
            catch (Exception)
            {
                throw;
            }

            return i;
        }

        /// <summary>
        /// 执行查询、查询多少条数据；返回第一行，第一列方法[ExecuteScalar] 返回-1执行失败
        /// </summary>
        /// <param name="sql">Sql命令</param>
        /// <param name="cmdtype">SQL语句（CommandType.Text）或者存储过程(CommandType.StoredProcedure)</param>
        /// <param name="pms"></param>
        /// <returns></returns>
        public static object ExecuteScalar(string sql, CommandType cmdtype, params SqlParameter[] pms)
        {
            try
            {
                using (SqlConnection con = new SqlConnection(constr))
                {
                    using (SqlCommand cmd = new SqlCommand(sql, con))
                    {
                        //存储过程或者Sql语句
                        cmd.CommandType = cmdtype;
                        if (pms != null)
                        {
                            cmd.Parameters.AddRange(pms);
                        }

                        con.Open();
                        return cmd.ExecuteScalar();
                    }
                }
            }
            catch (Exception)
            {
                throw;
            }
        }

        /// <summary>
        /// 执行查询，返回多行、多列的方法ExecuteReader()
        /// </summary>
        /// <param name="sql">Sql命令</param>
        /// <param name="cmdtype">SQL语句（CommandType.Text）或者存储过程(CommandType.StoredProcedure)</param>
        /// <param name="pms"></param>
        /// <returns></returns>
        public static SqlDataReader ExecuteReader(string sql, CommandType cmdtype, params SqlParameter[] pms)
        {
            SqlConnection con = new SqlConnection(constr);
            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                //存储过程或者Sql语句
                cmd.CommandType = cmdtype;
                if (pms != null)
                {
                    cmd.Parameters.AddRange(pms);
                }

                try
                {
                    con.Open();
                    return cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection);
                }
                catch
                {
                    con.Close();
                    con.Dispose();
                    throw;
                }
            }
        }

        /// <summary>
        /// 执行返回多个查询时使用,返回DataTable类型
        /// </summary>
        /// <param name="sql">Sql命令</param>
        /// <param name="cmdtype">SQL语句（CommandType.Text）或者存储过程(CommandType.StoredProcedure)</param>
        /// <param name="pms">参数</param>
        /// <returns></returns>
        public static DataTable ExecuteDataTable(string sql, CommandType cmdtype, params SqlParameter[] pms)
        {
            DataTable dt = new DataTable();
            try
            {
                //通过adapter读取数据。
                using (SqlDataAdapter adapter = new SqlDataAdapter(sql, constr))
                {
                    adapter.SelectCommand.CommandType = cmdtype;
                    if (pms != null)
                    {
                        adapter.SelectCommand.Parameters.AddRange(pms);
                    }

                    adapter.Fill(dt);
                    return dt;
                }
            }
            catch (Exception)
            {
                throw;
            }
        }

        /// <summary>
        /// 该方法是一个数据集方法在很多地方用得到的　
        /// </summary>
        /// <param name="sql">第一个参数是传sql语句</param>
        /// <param name="table">第二个参数是传数据库当中的表名</param>
        /// <returns></returns>
        public DataSet GetDataSet(string sql, CommandType cmdtype, string table)
        {
            try
            {
                using (SqlDataAdapter adapter = new SqlDataAdapter(sql, constr))
                {
                    adapter.SelectCommand.CommandType = cmdtype;
                    DataSet ds = new DataSet();
                    adapter.Fill(ds, table);
                    return ds;
                }
            }
            catch (Exception)
            {
                throw;
            }
        }
    }
}