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

namespace DB
{
    /// 

    /// DataBase 的摘要说明。
    /// 

    
    /// 

    /// 数据库连接类型
    /// 

    public enum dbType
    {
        /// 

        /// SQL数据库
        /// 

        sql,
        /// 

        /// access数据库
        /// 

        access
    }
    public class DataBase
    {
        // 连接数据源
        private SqlConnection con = null;
        private OleDbConnection conn = null;
        //连接数据类型
        dbType cType;
        public DataBase(string conStr,dbType type)
        {
            this.cType = type;
            if(type == dbType.sql)
                con = new SqlConnection(conStr);
            else if(type == dbType.access)
                conn = new OleDbConnection(conStr);
        }

        /// 

        /// 根据SQL查询返回DataSet对象，如果没有查询到则返回NULL
        /// 

        /// 查询语句
        /// DataSet
        public DataSet returnDS(string sql)
        {
            
            DataSet ds=new DataSet();
            try
            {
                if(cType == dbType.sql)
                {
                    SqlCommand cmd =new SqlCommand(sql,con);
                    cmd.CommandTimeout=20;
                    this.Open();
                    SqlDataAdapter adapter=new SqlDataAdapter(cmd);
                    adapter.Fill(ds,"tempTable");
                
                }
                else if(cType == dbType.access)
                {
                    OleDbCommand cmd = new OleDbCommand(sql,conn);
                    cmd.CommandTimeout=20;
                    this.Open();
                    System.Data.OleDb.OleDbDataAdapter adapter = new OleDbDataAdapter(cmd);
                    adapter.Fill(ds,"tempTable");
                }
            }
            catch(Exception e)
            {
                throw(e);
                ds = null;
            }
            finally
            {
                this.Close();    
            }

            return ds;
          
        }

        /// 

        /// 根据SQL查询返回DataSet对象，如果没有查询到则返回NULL
        /// 

        /// 查询语句
        /// 开始记录数
        /// 最大记录数
        /// DataSet
        public DataSet returnDS(string sql,int sRecord,int mRecord)
        {
            
            DataSet ds=new DataSet();
            try
            {
                if(cType == dbType.sql)
                {
                    SqlCommand cmd =new SqlCommand(sql,con);
                    cmd.CommandTimeout=20;
                    this.Open();
                    SqlDataAdapter adapter=new SqlDataAdapter(cmd);
                    adapter.Fill(ds,sRecord,mRecord,"tempTable");
                
                }
                else if(cType == dbType.access)
                {
                    OleDbCommand cmd = new OleDbCommand(sql,conn);
                    cmd.CommandTimeout=20;
                    this.Open();
                    System.Data.OleDb.OleDbDataAdapter adapter = new OleDbDataAdapter(cmd);
                    adapter.Fill(ds,sRecord,mRecord,"tempTable");
                }
            }
            catch(Exception e)
            {
                throw(e);
                ds = null;
            }
            finally
            {
                this.Close();    
            }

            return ds;
          
        }

        /// 

        /// 对数据库的增，删，改的操作
        /// 

        /// SQL语句
        /// 是否成功
        public bool OperateDB(string sql)
        {
            bool succeed=false;
            int cnt = 0;
            try
            {
                if(cType == dbType.sql)
                {
                    SqlCommand cmd = new SqlCommand(sql,con);
                    cmd.CommandTimeout = 20;
                    this.Open();
                    cnt = cmd.ExecuteNonQuery();
                
                }
                else if(cType == dbType.access)
                {
                    OleDbCommand cmd = new OleDbCommand(sql,conn);
                    cmd.CommandTimeout=20;
                    this.Open();
                    cnt = cmd.ExecuteNonQuery();
                }
            }
            catch(Exception e)
            {
                throw(e);
            }
            finally
            {
                if(cnt>0)
                {
                    succeed=true;
                }
                this.Close();
            }
                
            return succeed;
        }

        /// 

        /// 获得该SQL查询返回的第一行第一列的值，如果没有查询到则返回NULL
        /// 

        /// 查询语句
        /// 返回的第一行第一列的值
        public string getValue(string sql)
        {
            string str=null;
            try
            {
                if(cType == dbType.sql)
                {
                    SqlCommand cmd = new SqlCommand(sql,con);
                    this.Open();
                    str = cmd.ExecuteScalar().ToString();
                
                }
                else if(cType == dbType.access)
                {
                    OleDbCommand cmd = new OleDbCommand(sql,conn);
                    this.Open();
                    str = cmd.ExecuteScalar().ToString();
                }
            }
            catch(Exception e)
            {
                throw(e);
            }
            finally
            {
                this.Close();
            }
            
            return str;
        }        


        /// 

        ///  获得该SQL查询返回DataTable，如果没有查询到则返回NULL
        /// 

        /// 查询语句
        /// 
        public DataTable getTable(string sql)
        {
            DataTable tb = null;
            DataSet ds = this.returnDS(sql);
            if(ds != null)
            {
                tb = ds.Tables["tempTable"];
            }

            return tb;
        }
        
        /// 

        /// 打开数据库连接.
        /// 

        private void Open() 
        {
            if(cType == dbType.sql)
            {
                if(con.State == System.Data.ConnectionState.Closed)
                {
                    con.Open();
                }
                else if(con.State == System.Data.ConnectionState.Broken)
                {
                    con.Close();
                    con.Open();
                }
            }
            else if(cType == dbType.access)
            {
                if(conn.State == System.Data.ConnectionState.Closed)
                {
                    conn.Open();
                }
                else if(conn.State == System.Data.ConnectionState.Broken)
                {
                    conn.Close();
                    conn.Open();
                }
            }
        }

        /// 

        /// 关闭数据库连接
        /// 

        public void Close() 
        {
            if(cType == dbType.sql)
            {
                if (con != null)
                {
                    con.Close();
                }
            }
            else if(cType == dbType.access)
            {
                if (conn != null)
                {
                    conn.Close();
                }
            }
        }

        /// 

        /// 释放资源
        /// 

        public void Dispose() 
        {
            if(cType == dbType.sql)
            {
                // 确认连接是否已经关闭
                if (con != null) 
                {
                    con.Dispose();
                    con = null;
                }  
            }
            else if(cType == dbType.access)
            {
                if (conn != null) 
                {
                    conn.Dispose();
                    conn = null;
                }  
            }
  
        }

    }
}