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How Do I Use Gruop By Method In Charp Code To Covert DataTable? 分类汇总问题请教!

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悬赏园豆:10 [已解决问题] 解决于 2016-12-23 13:25

 

 

 

private System.Data.DataTable TestDataTable()
    {
        System.Data.DataTable oldDataTable = new DataTable();
        oldDataTable.Columns.Add("CheckinNum");
        oldDataTable.Columns.Add("CustomerAmount");
        oldDataTable.Columns.Add("ProviderAmount");
        oldDataTable.Columns.Add("AgentAmount");
        oldDataTable.Columns.Add("GrossAmount");
        oldDataTable.Columns.Add("TheMonth");

        int N=17; //N行数据;

        System.Data.DataRow dr = oldDataTable.NewRow(); 
        for (int i = 1; i < N; i++)
        {
            dr = oldDataTable.NewRow();
            dr["CheckinNum"] = 1;
            dr["CustomerAmount"] = 2;
            dr["ProviderAmount"] = 3;
            dr["AgentAmount"] = 4;
            dr["GrossAmount"] = 5;
            dr["TheMonth"] = i<=12?i:1;
            oldDataTable.Rows.Add(dr);
        }

        return oldDataTable;

        //转换思路:把oldDataTable按1到12进行分类汇总,就是卡在这里了...,汇总用foreach()
        //形如:                    
        /*
            foreach (DataRow dr in oldDataTable.Rows)        //关键点:根据(1 到12 月分来分类汇总,这里要怎样处理??
        {
            int CheckinNum = Convert.ToInt32(dr["CheckinNum"]);
            this.totalCheckinNum += CheckinNum;
            ........................................
        }
        */
    }
alone2013的主页 alone2013 | 初学一级 | 园豆:46
提问于:2014-01-17 17:54
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最佳答案
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Your have more questions!

Why not using sql statement to finish it?

You can use Linq method,for example 'GroupBy'!

收获园豆:10
幻天芒 | 高人七级 |园豆:36652 | 2014-01-17 22:35
//为了处理全量的12个月,那么先插入空数据
            for (var i = 1; i <= 12; i++)
            {
                oldDataTable.Rows.Add(0, 0, 0, 0, 0, i);//补全数据
            }
            var haha = oldDataTable.Rows.Cast<DataRow>().GroupBy(x => x["TheMonth"])
                .Select(x => new
                {
                    TheMonth = x.Key,
                    CheckinNum = x.Sum(x1 => Convert.ToInt32(x1["CheckinNum"])),
                    CustomerAmount = x.Sum(x1 => Convert.ToInt32(x1["CustomerAmount"])),
                    ProviderAmount = x.Sum(x1 => Convert.ToInt32(x1["ProviderAmount"])),
                    AgentAmount = x.Sum(x1 => Convert.ToInt32(x1["AgentAmount"])),
                    GrossAmount = x.Sum(x1 => Convert.ToInt32(x1["GrossAmount"]))
                }).ToList();
            //haha就是你需要的结果,是匿名类型的。

 

幻天芒 | 园豆:36652 (高人七级) | 2014-01-17 23:04

@幻天芒: 

 

Works beautifully. Thanks!

The datatable from a procedure,and I not permission opera the database.
So I don't know the procedure contains what tables...

In addtion,I want to study linq method solve problem.

How to Convert var to DataTable?
我想从haha中得到DataTable后,增加一个合计行,

但haha是匿名类型的,我不会处理了,如果是table就可以用 foreach 计算出和。

alone2013 | 园豆:46 (初学一级) | 2014-01-18 20:03

@alone2013:

First,you must create a new 'DataTable' and add columns;

Second,you can use 'Select' method to add rows.

幻天芒 | 园豆:36652 (高人七级) | 2014-01-19 23:26

@幻天芒: 

After created new 'DataTable',I don't know how convert the var to 'DataTable'...

alone2013 | 园豆:46 (初学一级) | 2014-01-20 09:27

@alone2013: Use loop

//定义匿名类型
            var haha = new[] { 1, 2, 3, 4 }.Select(x => new { C1 = x, C2 = x * 2, C3 = x * 3 });
            //转换为DataTable
            //创建DataTable并设定列
            var dt = new DataTable();
            dt.Columns.Add("C1", typeof(int));
            dt.Columns.Add("C2", typeof(int));
            dt.Columns.Add("C3", typeof(int));

            //处理rows
            foreach (var x in haha)
            {
                dt.Rows.Add(x.C1, x.C2, x.C3);
            }
幻天芒 | 园豆:36652 (高人七级) | 2014-01-20 11:49

@幻天芒: 

ok,I know.

Thank you so much for all your patience, guidance!

alone2013 | 园豆:46 (初学一级) | 2014-01-20 13:31
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