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  • DbHelper-SQL数据库访问助手

    using System;
    using System.Data;
    using System.Data.SqlClient;
    
    namespace Whir.Software.Framework.Ultimate
    {
        /// <summary>
        ///     数据库访问助手
        /// </summary>
        public class DbHelper
        {
            #region 判断连接是否成功
            /// <summary>
            ///     判断连接是否成功!
            /// </summary>
            /// <param name="con"> 链接字符串</param>
            /// <returns>true 表示链接成功,false表示连接失败</returns>
            public static bool IsConnected(string con)
            {
                bool flag;
                var conn = new SqlConnection(con);
                try
                {
                    conn.Open();
                    flag = true;
                }
                catch (Exception)
                {
                    flag = false;
                }
                finally
                {
                    conn.Close();
                }
                return flag;
            }
            #endregion
            #region 执行不带参数sql语句
            /// <summary>
            ///     执行不带参数sql语句
            /// </summary>
            /// <param name="sql">增,删,改sql语句</param>
            /// <param name="con"></param>
            /// <returns>返回所影响的行数</returns>
            public static bool Execute(string sql, string con)
            {
                var cmd = new SqlCommand();
                var connection = new SqlConnection(con);
                try
                {
                    using (connection)
                    {
                        cmd.Connection = connection;
                        cmd.CommandText = sql;
                        connection.Open();
                        cmd.ExecuteNonQuery();
                        return true;
                    }
                }
                catch (Exception)
                {
                    return false;
                }
            }
            #endregion
            #region 执行SQL语句返回DataTable
            /// <summary>
            ///     执行SQL语句返回DataTable
            /// </summary>
            /// <param name="sql"></param>
            /// <param name="con"></param>
            /// <returns></returns>
            public static DataTable ExcuteDataTable(string sql, string con)
            {
                var cmd = new SqlCommand();
                var connection = new SqlConnection(con);
                try
                {
                    using (connection)
                    {
                        cmd.Connection = connection;
                        cmd.CommandText = sql;
                        connection.Open();
                        var da = new SqlDataAdapter(cmd);
                        var ds = new DataSet();
                        da.Fill(ds);
                        return ds.Tables[0];
                    }
                }
                catch (Exception ex)
                {
                    var dt = new DataTable();
                    dt.Columns.Add("异常信息");
                    DataRow row = dt.NewRow();
                    row["异常信息"] = ex.Message;
                    dt.Rows.Add(row);
                    return dt;
                }
            }
            #endregion
            #region 执行SQL语句查询单条记录
            /// <summary>
            ///     执行SQL语句查询单条记录
            /// </summary>
            /// <param name="sql"></param>
            /// <param name="con"></param>
            /// <returns></returns>
            public static object ExecuteScalar(string sql, string con)
            {
                var cmd = new SqlCommand();
                var connection = new SqlConnection(con);
                try
                {
                    using (connection)
                    {
                        cmd.Connection = connection;
                        cmd.CommandText = sql;
                        connection.Open();
                        return cmd.ExecuteScalar();
                    }
                }
                catch (Exception)
                {
                    return string.Empty;
                }
            }
            #endregion
            #region 取得表最大Id
            /// <summary>
            ///     取得表最大Id
            /// </summary>
            /// <param name="tableName"></param>
            /// <param name="fieldName"></param>
            /// <param name="con"></param>
            /// <returns></returns>
            public static int GetMaxId(string tableName, string fieldName, string con)
            {
                string sql = "SELECT NVL(MAX({0}),0)+1 FROM {1}";
                try
                {
                    sql = string.Format(sql, fieldName, tableName);
                    int result;
                    Int32.TryParse(ExecuteScalar(sql, con).ToString(), out result);
                    return result;
                }
                catch (Exception)
                {
                    return -1;
                }
            }
            #endregion
        }
    }

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  • 原文地址:https://www.cnblogs.com/zhangqs008/p/3763798.html
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