C#DataTable一些基本操作_c# datatable where

一.C#创建datatable

1.新增列

 DataTable dt = new DataTable();
            dt.Columns.Add("studentName", typeof(string));
            dt.Columns.Add("studentSex", typeof(string));
            dt.Columns.Add("delivery_day", typeof(string));

2.添加行

//第一种方式
 dt.Rows.Add("xx","女","2022/01/01");
//第二种方式
 DataRow dr = dt.NewRow();
  dr["studentName"] = "001";
  dr["studentSex"] = "男";
  dr["delivery_day"]="2022/12/12";
 dt.Rows.Add(dr);

3. C#普通查询

//第一种
 DataTable dt1 = dataGridView1.DataSource as DataTable;//
            var row = dt1.AsEnumerable()
           .Where(p => p.Field<string>("studentSex") == "女")
           .Select(p => new
           {
               studentName = p.Field<string>("studentName"),
               studentSex = p.Field<string>("studentSex"),
               delivery_day = p.Field<string>("delivery_day")
           });
            dataGridView1.DataSource = row.ToList();
//第二种
DataTable dt2 = dataGridView1.DataSource as DataTable;
            var row = dt2.AsEnumerable().Where<DataRow>(p => p["studentSex"].ToString() == "女");
            //两种绑定方式
            dataGridView1.DataSource = row.CopyToDataTable();
            //dataGridView1.DataSource = row.AsDataView().ToTable();
//第三种
DataTable dt3 = dataGridView1.DataSource as DataTable;
            DataView dv = dt3.AsDataView();
            dv.RowFilter = "studentSex='男'";
            dataGridView1.DataSource = dv;
//第四种
 DataTable dt4 = dataGridView1.DataSource as DataTable;
            var row4 = dt4.Select("studentSex='男' and studentName like 'xiaoming%' ");
            dataGridView1.DataSource = row4.CopyToDataTable();

5.排序 

 DataTable dt4 = dataGridView1.DataSource as DataTable;
    DataView dv = new DataView(dt4);
  dv.Sort = "studentSex desc";

以下链接说的很详细

https://www.cnblogs.com/lxshanye/archive/2013/03/13/2957334.html

6.分组group by

 var query = from g in dataTable.AsEnumerable()
                                group g by new
                                {
                                    t1 = g.Field<string>("Column13"),
                                    t2 = g.Field<string>("Column7"),
 
                                } into products
 
                                select new
                                {
                                    t1 = products.Key.t1,
                                    t2 = products.Key.t2,
                                    t3 = products.Sum(n => Convert.ToDecimal(n.Field<string>("Column6"))),
                                    t4 = products.Sum(n => Convert.ToDecimal(n.Field<string>("Column8"))),
                                    t5 = 1.00,
                                    t6 = products.Sum(n => Convert.ToDecimal(n.Field<string>("Column10"))),
                                    t7 = products.Average(n => Convert.ToDecimal(n.Field<string>("Column11"))).ToString("0.00"),
                                    t8 = products.Sum(n => Convert.ToDecimal(n.Field<string>("Column6"))) == 0 ? "0" : ((products.Sum(n => Convert.ToDecimal(n.Field<string>("Column10"))) / products.Sum(n => Convert.ToDecimal(n.Field<string>("Column6")))) * 100).ToString("0.00")
                                    //t8 = products.Average(n => Convert.ToDecimal(n.Field<string>("Column12"))).ToString("0.00")
                                };
                    this.dataGridView2.DataSource = query.ToList();