最近在做报表统计方面的需求，涉及到行转列报表。根据以往经验使用SQL可以比较容易完成，这次决定挑战一下直接通过代码方式完成行转列。期间遇到几个问题和用到的新知识这里整理记录一下。

阅读目录

• 问题介绍

• 动态Linq

• System.Linq.Dynamic其它用法

• DataTable行转列

• 总结

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问题介绍

　　以家庭月度费用为例，可以在[Name,Area,Month]三个维度上随意组合进行分组，三个维度中选择一个做为列显示。

    /// <summary>    /// 家庭费用情况    /// </summary>    public class House    {        /// <summary>        /// 户主姓名        /// </summary>        public string Name { get; set; }        /// <summary>        /// 所属行政区域        /// </summary>        public string Area { get; set; }        /// <summary>        /// 月份        /// </summary>        public string Month { get; set; }        /// <summary>        /// 电费金额        /// </summary>        public double DfMoney { get; set; }        /// <summary>        /// 水费金额        /// </summary>        public double SfMoney { get; set; }        /// <summary>        /// 燃气金额        /// </summary>        public double RqfMoney { get; set; }    }

    现在后台查出来的数据是List<House>类型，前台传过来分组维度和动态列字段。  第1个表格前台传给后台参数

{DimensionList:['Name'],DynamicColumn:'Month'}

 第2个表格前台传给后台参数

{DimensionList:['Area'],DynamicColumn:'Month'}

第3个表格前台传给后台参数

{DimensionList:['Area','Month'],DynamicColumn:'Name'}

问题描述清楚后，仔细分析后你就会发现这里的难题在于动态分组，也就是怎么根据前台传过来的多个维度对List进行分组。回到顶部 

动态Linq

   下面使用System.Linq.Dynamic完成行转列功能，Nuget上搜索System.Linq.Dynamic即可下载该包。

   代码进行了封装，实现了通用的List<T>行转列功能。

        /// <summary>        /// 动态Linq方式实现行转列        /// </summary>        /// <param name="list">数据</param>        /// <param name="DimensionList">维度列</param>        /// <param name="DynamicColumn">动态列</param>        /// <returns>行转列后数据</returns>        private static List<dynamic> DynamicLinq<T>(List<T> list, List<string> DimensionList, string DynamicColumn, out List<string> AllDynamicColumn) where T : class        {            //获取所有动态列            var columnGroup = list.GroupBy(DynamicColumn, "new(it as Vm)") as IEnumerable<IGrouping<dynamic, dynamic>>;            List<string> AllColumnList = new List<string>();            foreach (var item in columnGroup)            {                if (!string.IsNullOrEmpty(item.Key))                {                    AllColumnList.Add(item.Key);                }            }            AllDynamicColumn = AllColumnList;            var dictFunc = new Dictionary<string, Func<T, bool>>();            foreach (var column in AllColumnList)            {                var func = DynamicExpression.ParseLambda<T, bool>(string.Format("{0}==\"{1}\"", DynamicColumn, column)).Compile();                dictFunc[column] = func;            }            //获取实体所有属性            Dictionary<string, PropertyInfo> PropertyInfoDict = new Dictionary<string, PropertyInfo>();            Type type = typeof(T);            var propertyInfos = type.GetProperties(BindingFlags.Instance | BindingFlags.Public);            //数值列            List<string> AllNumberField = new List<string>();            foreach (var item in propertyInfos)            {                PropertyInfoDict[item.Name] = item;                if (item.PropertyType == typeof(int) || item.PropertyType == typeof(double) || item.PropertyType == typeof(float))                {                    AllNumberField.Add(item.Name);                }            }            //分组            var dataGroup = list.GroupBy(string.Format("new ({0})", string.Join(",", DimensionList)), "new(it as Vm)") as IEnumerable<IGrouping<dynamic, dynamic>>;            List<dynamic> listResult = new List<dynamic>();            IDictionary<string, object> itemObj = null;            T vm2 = default(T);            foreach (var group in dataGroup)            {                itemObj = new ExpandoObject();                var listVm = group.Select(e => e.Vm as T).ToList();                //维度列赋值                vm2 = listVm.FirstOrDefault();                foreach (var key in DimensionList)                {                    itemObj[key] = PropertyInfoDict[key].GetValue(vm2);                }                foreach (var column in AllColumnList)                {                    vm2 = listVm.FirstOrDefault(dictFunc[column]);                    if (vm2 != null)                    {                        foreach (string name in AllNumberField)                        {                            itemObj[name + column] = PropertyInfoDict[name].GetValue(vm2);                        }                    }                }                listResult.Add(itemObj);            }            return listResult;        }

   标红部分使用了System.Linq.Dynamic动态分组功能，传入字符串即可分组。使用了dynamic类型，关于dynamic介绍可以参考其它文章介绍哦。

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System.Linq.Dynamic其它用法

    上面行转列代码见识了System.Linq.Dynamic的强大，下面再介绍一下会在开发中用到的方法。

    Where过滤

list.Where("Name=@0", "张三")

上面用到了参数化查询，实现了查找姓名是张三的数据，通过这段代码你或许感受不到它的好处。但是和EntityFramework结合起来就可以实现动态拼接SQL的功能了。

        /// <summary>        /// EF实体查询封装         /// </summary>        /// <typeparam name="T">实体类型</typeparam>        /// <param name="Query">IQueryable对象</param>        /// <param name="gridParam">过滤条件</param>        /// <returns>查询结果</returns>        public static EFPaginationResult<T> PageQuery<T>(this IQueryable<T> Query, QueryCondition gridParam)        {            //查询条件            EFFilter filter = GetParameterSQL<T>(gridParam);            var query = Query.Where(filter.Filter, filter.ListArgs.ToArray());            //查询结果            EFPaginationResult<T> result = new EFPaginationResult<T>();            if (gridParam.IsPagination)            {                int PageSize = gridParam.PageSize;                int PageIndex = gridParam.PageIndex < 0 ? 0 : gridParam.PageIndex;                //获取排序信息                string sort = GetSort(gridParam, typeof(T).FullName);                result.Data = query.OrderBy(sort).Skip(PageIndex * PageSize).Take(PageSize).ToList<T>();                if (gridParam.IsCalcTotal)                {                    result.Total = query.Count();                    result.TotalPage = Convert.ToInt32(Math.Ceiling(result.Total * 1.0 / PageSize));                }                else                {                    result.Total = result.Data.Count();                }            }            else            {                result.Data = query.ToList();                result.Total = result.Data.Count();            }            return result;        }

/// <summary>        /// 通过查询条件,获取参数化查询SQL        /// </summary>        /// <param name="gridParam">过滤条件</param>        /// <returns>过滤条件字符</returns>        private static EFFilter GetParameterSQL<T>(QueryCondition gridParam)        {            EFFilter result = new EFFilter();            //参数值集合            List<object> listArgs = new List<object>();            string filter = "1=1";            #region "处理动态过滤条件"            if (gridParam.FilterList != null && gridParam.FilterList.Count > 0)            {                StringBuilder sb = new StringBuilder();                int paramCount = 0;                DateTime dateTime;                //操作符                string strOperator = string.Empty;                foreach (var item in gridParam.FilterList)                {                    //字段名称为空则跳过                    if (string.IsNullOrEmpty(item.FieldName))                    {                        continue;                    }                    //匹配枚举，防止SQL注入                    Operator operatorEnum = (Operator)Enum.Parse(typeof(Operator), item.Operator, true);                    //跳过字段值为空的                    if (operatorEnum != Operator.Null && operatorEnum != Operator.NotNull && string.IsNullOrEmpty(item.FieldValue))                    {                        continue;                    }                    strOperator = operatorEnum.GetDescription();                    if (item.IgnoreCase && !item.IsDateTime)                    {                        //2016-07-19添加查询时忽略大小写比较                        item.FieldValue = item.FieldValue.ToLower();                        item.FieldName = string.Format("{0}.ToLower()", item.FieldName);                    }                    switch (operatorEnum)                    {                        //等于,不等于，小于，大于，小于等于，大于等于                        case Operator.EQ:                        case Operator.NE:                        case Operator.GT:                        case Operator.GE:                        case Operator.LT:                        case Operator.LE:                            if (item.IsDateTime)                            {                                if (DateTime.TryParse(item.FieldValue, out dateTime))                                {                                    if (!item.FieldValue.Contains("00:00:00") && dateTime.ToString("HH:mm:ss") == "00:00:00")                                    {                                        if (operatorEnum == Operator.LE)                                        {                                            listArgs.Add(DateTime.Parse(dateTime.ToString("yyyy-MM-dd") + " 23:59:59"));                                        }                                        else                                        {                                            listArgs.Add(dateTime);                                        }                                    }                                    else                                    {                                        listArgs.Add(dateTime);                                    }                                    sb.AppendFormat(" AND {0} {1} @{2}", item.FieldName, strOperator, paramCount);                                }                            }                            else                            {                                listArgs.Add(ConvertToType(item.FieldValue, GetPropType<T>(item.FieldName)));                                sb.AppendFormat(" AND {0} {1} @{2}", item.FieldName, strOperator, paramCount);                            }                            paramCount++;                            break;                        case Operator.Like:                        case Operator.NotLike:                        case Operator.LLike:                        case Operator.RLike:                            listArgs.Add(item.FieldValue);                            if (operatorEnum == Operator.Like)                            {                                sb.AppendFormat(" AND {0}.Contains(@{1})", item.FieldName, paramCount);                            }                            else if (operatorEnum == Operator.NotLike)                            {                                sb.AppendFormat(" AND !{0}.Contains(@{1})", item.FieldName, paramCount);                            }                            else if (operatorEnum == Operator.LLike)                            {                                sb.AppendFormat(" AND {0}.EndsWith(@{1})", item.FieldName, paramCount);                            }                            else if (operatorEnum == Operator.RLike)                            {                                sb.AppendFormat(" AND {0}.StartsWith(@{1})", item.FieldName, paramCount);                            }                            paramCount++;                            break;                        case Operator.Null:                            listArgs.Add(item.FieldValue);                            sb.AppendFormat(" AND {0}=null", item.FieldName);                            paramCount++;                            break;                        case Operator.NotNull:                            listArgs.Add(item.FieldValue);                            sb.AppendFormat(" AND {0}!=null", item.FieldName);                            paramCount++;                            break;                        case Operator.In:                            sb.AppendFormat(" AND (");                            foreach (var schar in item.FieldValue.Split(','))                            {                                listArgs.Add(schar);                                sb.AppendFormat("{0}=@{1} or ", item.FieldName, paramCount);                                paramCount++;                            }                            sb.Remove(sb.Length - 3, 3);                            sb.AppendFormat(" )");                            break;                        case Operator.NotIn:                            sb.AppendFormat(" AND (");                            foreach (var schar in item.FieldValue.Split(','))                            {                                listArgs.Add(schar);                                sb.AppendFormat("{0}!=@{1} and ", item.FieldName, paramCount);                                paramCount++;                            }                            sb.Remove(sb.Length - 3, 3);                            sb.AppendFormat(" )");                            break;                    }                    if (sb.ToString().Length > 0)                    {                        filter = sb.ToString().Substring(4, sb.Length - 4);                    }                }                #endregion            }            result.Filter = filter;            result.ListArgs = listArgs;            return result;        }

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DataTable行转列

　　该部分是根据网友反馈后期再补充上的内容，意在完善行转列。下面给出实现代码

using Newtonsoft.Json;using System;using System.Collections.Generic;using System.Data;using System.Linq;using System.Text;using System.Threading.Tasks;namespace DataTable_RowToColumn{    class Program    {        static void Main(string[] args)        {            DataTable dt = InitTable();            List<string> DimensionList = new List<string>() { "Area", "Month" };            string DynamicColumn = "Name";            List<string> AllDynamicColumn = null;            DataTable dtResult = RowToColumn(dt, DimensionList, DynamicColumn, out AllDynamicColumn);            Console.WriteLine(JsonConvert.SerializeObject(dtResult, Formatting.Indented));            Console.Read();        }        /// <summary>        /// 动态Linq方式实现行转列        /// </summary>        /// <param name="list">数据</param>        /// <param name="DimensionList">维度列</param>        /// <param name="DynamicColumn">动态列</param>        /// <returns>行转列后数据</returns>        private static DataTable RowToColumn(DataTable dt, List<string> DimensionList, string DynamicColumn, out List<string> AllDynamicColumn)        {            //获取所有动态列            AllDynamicColumn = new List<string>();            foreach (DataRow dr in dt.DefaultView.ToTable(true, DynamicColumn).Rows)            {                if (dr[DynamicColumn] != null && !string.IsNullOrEmpty(dr[DynamicColumn].ToString()))                {                    AllDynamicColumn.Add(dr[DynamicColumn].ToString());                }            }            //数值列            Dictionary<string, Type> AllNumberColumn = new Dictionary<string, Type>();            foreach (DataColumn item in dt.Columns)            {                if (item.DataType == typeof(int) || item.DataType == typeof(double) || item.DataType == typeof(float))                {                    AllNumberColumn.Add(item.ColumnName, item.DataType);                }            }            //结果DataTable创建            DataTable dtResult = new DataTable();            foreach (var item in DimensionList)            {                dtResult.Columns.Add(item, typeof(string));            }            //动态列            foreach (var dynamicValue in AllDynamicColumn)            {                foreach (var item in AllNumberColumn.Keys)                {                    dtResult.Columns.Add(item + dynamicValue, AllNumberColumn[item]);                }            }            //分组            var dtGroup = dt.DefaultView.ToTable(true, DimensionList.ToArray());            foreach (DataRow dr in dtGroup.Rows)            {                DataRow drReult = dtResult.NewRow();                string filter = "";                foreach (var key in DimensionList)                {                    drReult[key] = dr[key];                    filter += key + "='" + dr[key] + "' AND ";                }                string dynamicFilter = "";                foreach (var dynamicValue in AllDynamicColumn)                {                    dynamicFilter = DynamicColumn + "='" + dynamicValue + "'";                    foreach (var numColumn in AllNumberColumn.Keys)                    {                        drReult[numColumn + dynamicValue] = dt.Compute("sum(" + numColumn + ")", filter + dynamicFilter);                    }                }                dtResult.Rows.Add(drReult);            }            return dtResult;        }        private static DataTable InitTable()        {            DataTable dt = new DataTable();            dt.Columns.Add("Name", typeof(string));            dt.Columns.Add("Area", typeof(string));            dt.Columns.Add("Month", typeof(string));            dt.Columns.Add("DfMoney", typeof(double));            dt.Columns.Add("SfMoney", typeof(double));            dt.Columns.Add("RqfMoney", typeof(double));            DataRow row = dt.NewRow();            row["Name"] = "张三";            row["Month"] = "2016-01";            row["Area"] = "江夏区";            row["DfMoney"] = 240.9;            row["SfMoney"] = 30;            row["RqfMoney"] = 25;            dt.Rows.Add(row);            row = dt.NewRow();            row["Name"] = "张三";            row["Month"] = "2016-02";            row["Area"] = "江夏区";            row["DfMoney"] = 167;            row["SfMoney"] = 24.5;            row["RqfMoney"] = 17.9;            dt.Rows.Add(row);            row = dt.NewRow();            row["Name"] = "小燕子";            row["Month"] = "2016-01";            row["Area"] = "江夏区";            row["DfMoney"] = 340.9;            row["SfMoney"] = 20;            row["RqfMoney"] = 55;            dt.Rows.Add(row);            row = dt.NewRow();            row["Name"] = "小燕子";            row["Month"] = "2016-02";            row["Area"] = "江夏区";            row["DfMoney"] = 67;            row["SfMoney"] = 64.5;            row["RqfMoney"] = 77.9;            dt.Rows.Add(row);            row = dt.NewRow();            row["Name"] = "李四";            row["Month"] = "2016-01";            row["Area"] = "洪山区";            row["DfMoney"] = 56.7;            row["SfMoney"] = 24.7;            row["RqfMoney"] = 13.2;            dt.Rows.Add(row);            row = dt.NewRow();            row["Name"] = "李四";            row["Month"] = "2016-02";            row["Area"] = "洪山区";            row["DfMoney"] = 65.2;            row["SfMoney"] = 18.9;            row["RqfMoney"] = 14.9;            dt.Rows.Add(row);            row = dt.NewRow();            row["Name"] = "尔康";            row["Month"] = "2016-01";            row["Area"] = "洪山区";            row["DfMoney"] = 156.7;            row["SfMoney"] = 124.7;            row["RqfMoney"] = 33.2;            dt.Rows.Add(row);            row = dt.NewRow();            row["Name"] = "尔康";            row["Month"] = "2016-02";            row["Area"] = "洪山区";            row["DfMoney"] = 35.2;            row["SfMoney"] = 28.9;            row["RqfMoney"] = 44.9;            dt.Rows.Add(row);            return dt;        }    }}

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总结

      本篇通过行转列引出了System.Linq.Dynamic，并且介绍了过滤功能，其实它的用处还有很多，等待大家发掘。下面给出本文示例代码：DynamicLinq

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