SQL数据库连接

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

namespace DAL
{
    public class cls_SQLFunction
    {
        string connectionString = "";
        System.Configuration.ConnectionStringSettings connString = System.Configuration.ConfigurationManager.ConnectionStrings["K3ConnectionString"];

        /// <summary>
        /// 读取数据库
        /// </summary>
        /// <param name="ComTxt">数据库查询语句</param>
        /// <param name="TableName">表名</param>
        /// <returns>查询结果——数据集</returns>
        public DataSet Read_DataSet(string ComTxt, string TableName)
        {
            try
            {
                if (null != connString)
                {
                    connectionString = connString.ConnectionString;
                }
                SqlConnection con;
                SqlCommand selectcmd;
                con = new SqlConnection(connectionString);
                con.Open();
                selectcmd = new SqlCommand();
                selectcmd.CommandText = ComTxt;
                selectcmd.CommandTimeout = 1800;
                SqlDataAdapter adapter = new SqlDataAdapter(selectcmd.CommandText, con);
                adapter.SelectCommand.CommandTimeout = 1800;
                DataSet ds = new DataSet();
                adapter.Fill(ds, TableName);
                DataTable dt = ds.Tables[TableName];
                con.Close();
                return ds;
            }
            catch
            {
                DataSet ds = new DataSet();
                ds = null;
                return ds;
            }
        }

        //--------------------------------------------------------------------------------
        /// <summary>
        /// 插入、删除、修改数据库
        /// </summary>
        /// <param name="ComTxt">SQL语句</param>
        public bool SQLUpdate(string ComTxt)
        {
            try
            {
                if (null != connString)
                {
                    connectionString = connString.ConnectionString;
                }
                SqlConnection con;
                SqlCommand selectcmd;
                con = new SqlConnection(connectionString);
                con.Open();
                selectcmd = new SqlCommand();
                selectcmd.Connection = con;
                selectcmd.CommandText = ComTxt;　　//执行TSQL、表名、存储过程、一段SQL语句
                selectcmd.ExecuteNonQuery();
                con.Close();
                return true;
            }
            catch
            {
                return false;
            }
        }

        //--------------------------------------------------------------------------------
        /// <summary>
        /// 数据库二进制数据写入
        /// </summary>
        /// <param name="ComTxt">SQL语句</param>
        /// <param name="File">文件二进制流</param>
        /// <returns>是否写入成功</returns>
        public bool SQLUpdate_Photo(string ComTxt, byte[] File)
        {
            try
            {
                if (null != connString)
                {
                    connectionString = connString.ConnectionString;
                }
                SqlConnection con;
                SqlCommand selectcmd;
                con = new SqlConnection(connectionString);
                con.Open();
                selectcmd = new SqlCommand(ComTxt, con);
                selectcmd.Parameters.Add("@File", SqlDbType.Image);
                selectcmd.Parameters[0].Value = File;
                selectcmd.ExecuteNonQuery();
                con.Close();
                return true;
            }
            catch
            {
                return false;
            }
        }
    }
}