内存表合并两个DaTaTable
/// <summary>
/// 建立两内存表的链接
/// </summary>
/// <param name="dt1">左表（主表）</param>
/// <param name="dt2">右表</param>
/// <param name="FJC">左表中关联的字段名（字符串）</param>
/// <param name="SJC">右表中关联的字段名（字符串）</param>
/// https://www.cnblogs.com/xuke/p/4049427.html
/// <returns></returns>
public static DataTable Join(DataTable dt1, DataTable dt2, DataColumn[] FJC, DataColumn[] SJC)
{
//创建一个新的DataTable
DataTable table = new DataTable("Join");
// Use a DataSet to leverage DataRelation
using (DataSet ds = new DataSet())
{
//把DataTable Copy到DataSet中
ds.Tables.AddRange(new DataTable[] { dt1.Copy(), dt2.Copy() });
DataColumn[] First_columns = new DataColumn[FJC.Length];
for (int i = 0; i < First_columns.Length; i++)
{
First_columns[i] = ds.Tables[0].Columns[FJC[i].ColumnName];
}
DataColumn[] Second_columns = new DataColumn[SJC.Length];
for (int i = 0; i < Second_columns.Length; i++)
{
Second_columns[i] = ds.Tables[1].Columns[SJC[i].ColumnName];
}
//创建关联
DataRelation r = new DataRelation(string.Empty, First_columns, Second_columns, false);
ds.Relations.Add(r);
//为关联表创建列
for (int i = 0; i < dt1.Columns.Count; i++)
{
table.Columns.Add(dt1.Columns[i].ColumnName, dt1.Columns[i].DataType);
}
for (int i = 0; i < dt2.Columns.Count; i++)
{
//看看有没有重复的列，如果有在第二个DataTable的Column的列明后加_Second
if (!table.Columns.Contains(dt2.Columns[i].ColumnName))
table.Columns.Add(dt2.Columns[i].ColumnName, dt2.Columns[i].DataType);
else
table.Columns.Add(dt2.Columns[i].ColumnName + "_Second", dt2.Columns[i].DataType);
}
table.BeginLoadData();
int itable2Colomns = ds.Tables[1].Rows[0].ItemArray.Length;
foreach (DataRow firstrow in ds.Tables[0].Rows)
{
//得到行的数据
DataRow[] childrows = firstrow.GetChildRows(r);//第二个表关联的行
if (childrows != null && childrows.Length > 0)
{
object[] parentarray = firstrow.ItemArray;
foreach (DataRow secondrow in childrows)
{
object[] secondarray = secondrow.ItemArray;
object[] joinarray = new object[parentarray.Length + secondarray.Length];
Array.Copy(parentarray, 0, joinarray, 0, parentarray.Length);
Array.Copy(secondarray, 0, joinarray, parentarray.Length, secondarray.Length);
table.LoadDataRow(joinarray, true);
}
}
else//如果有外连接(Left Join)添加这部分代码
{
object[] table1array = firstrow.ItemArray;//Table1
object[] table2array = new object[itable2Colomns];
object[] joinarray = new object[table1array.Length + itable2Colomns];
Array.Copy(table1array, 0, joinarray, 0, table1array.Length);
Array.Copy(table2array, 0, joinarray, table1array.Length, itable2Colomns);
table.LoadDataRow(joinarray, true);
DataColumn[] dc = new DataColumn[2];
dc[0] = new DataColumn("");
}
}
table.EndLoadData();
}
return table;//***在此处打断点，程序运行后点击查看即可观察到结果
}
/// <summary>
/// 重载1
/// </summary>
/// <param name="dt1"></param>
/// <param name="dt2"></param>
/// <param name="FJC"></param>
/// <param name="SJC"></param>
/// <returns></returns>
public static DataTable Join(DataTable dt1, DataTable dt2, DataColumn FJC, DataColumn SJC)
{
return Join(dt1, dt2, new DataColumn[] { FJC }, new DataColumn[] { SJC });
}
/// <summary>
/// 重载2
/// </summary>
/// <param name="dt1"></param>
/// <param name="dt2"></param>
/// <param name="FJC"></param>
/// <param name="SJC"></param>
/// <returns></returns>
public static DataTable Join(DataTable dt1, DataTable dt2, string FJC, string SJC)
{
return Join(dt1, dt2, new DataColumn[] { dt1.Columns[FJC] }, new DataColumn[] { dt1.Columns[SJC] });
}
*注: 多个外键,请用——重载1
public static DataTable ProductInfo(DataTable dt1, DataTable dt2, string FJC, string SJC)
{
DataTable dt1 = ProductBLL.GetList();//主表,主键是:pro_id
DataTable dt2 = ProductSubBLL.GetList();//子表,外键是:pro_id
return Join(dt1, dt2,"pro_id","pro_id"});//重载2
}
用Linq连接两个DataTable
using System.Linq;
public DataTable ProductInfoList(string month, string CINVCODE)
{
DataTable dt1 = ProductBLL.GetList();
DataTable dt2 = ProductSubBLL.GetList();
//合并两个dt的表结构(表头)
DataTable dt3 = dt1.Clone();
for (int i = 0; i < dt2.Columns.Count; i++)
{
if (dt2.Columns[i].ToString() == "ProductID")
{
continue;
}
else
{
string ColName = dt2.Columns[i].ToString();//表头
dt3.Columns.Add(ColName, typeof(decimal));//字段类型
}
}
var query = from a in dt1.AsEnumerable()
join b in dt2.AsEnumerable()
on a.Field<string>("ProductID") equals b.Field<string>("ProductID")
select a.ItemArray.Concat(b.ItemArray.Skip(1));//Skip(1): 跳过 "ProductID" 列,不添加
foreach (var obj in query)
{
DataRow dr = dt3.NewRow();
dr.ItemArray = obj.ToArray();
dt3.Rows.Add(dr);
}
return dt3;
}
