1.将泛型集合类转换成DataTable（表中无数据时使用）：
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public static DataTable NullListToDataTable(IList list)
{
var result = new DataTable();
if (list.Count <= 0) return result;
var propertys = list[0].GetType().GetProperties();
foreach (var pi in propertys)
{
if (pi != null)
{
result.Columns.Add(pi.Name, pi.PropertyType);
}
}
for (var i = 0; i < list.Count; i++)
{
var tempList = new ArrayList();
foreach (var pi in propertys)
{
var obj = pi.GetValue(list[i], null);
tempList.Add(obj);
}
var array = tempList.ToArray();
result.LoadDataRow(array, true);
}
return result;
}2.将泛型集合类转换成DataTable（表中有数据时使用）：
public static DataTable NoNullListToDataTable(IList list) { var ds = new DataSet(); var dt = new DataTable(typeof(T).Name); var myPropertyInfo = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance); foreach (var t in list) { if (t == null) continue; var row = dt.NewRow(); for (int i = 0, j = myPropertyInfo.Length; i < j; i++) { var pi = myPropertyInfo[i]; var name = pi.Name; if (dt.Columns[name] != null) continue; DataColumn column; if (pi.PropertyType.UnderlyingSystemType.ToString() == "System.Nullable`1[System.Int32]") { column = new DataColumn(name, typeof(int)); dt.Columns.Add(column); if (pi.GetValue(t, null) != null) row[name] = pi.GetValue(t, null); else row[name] = DBNull.Value; } else { column = new DataColumn(name, pi.PropertyType); dt.Columns.Add(column); row[name] = pi.GetValue(t, null); } } dt.Rows.Add(row); } ds.Tables.Add(dt); return ds.Tables[0]; }
3.表中有数据或无数据时使用,可排除DATASET不支持System.Nullable错误：
public static DataTable ToDataTable(IList list) { if (list == null || list.Count <= 0) { var result = new DataTable(); object temp; if (list == null || list.Count <= 0) return result; var propertys = list[0].GetType().GetProperties(); foreach (var pi in propertys) { { result.Columns.Add(pi.Name, pi.PropertyType); } } for (var i = 0; i < list.Count; i++) { var tempList = new ArrayList(); foreach (var pi in propertys) { var obj = pi.GetValue(list[i], null); tempList.Add(obj); } var array = tempList.ToArray(); result.LoadDataRow(array, true); } return result; } var ds = new DataSet(); var dt = new DataTable(typeof(T).Name); var myPropertyInfo = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance); foreach (var t in list) { if (t == null) continue; var row = dt.NewRow(); for (int i = 0, j = myPropertyInfo.Length; i < j; i++) { var pi = myPropertyInfo[i]; var name = pi.Name; if (dt.Columns[name] != null) continue; DataColumn column; if (pi.PropertyType.UnderlyingSystemType.ToString() == "System.Nullable`1[System.Int32]") { column = new DataColumn(name, typeof(int)); dt.Columns.Add(column); if (pi.GetValue(t, null) != null) row[name] = pi.GetValue(t, null); else row[name] = DBNull.Value; } else { column = new DataColumn(name, pi.PropertyType); dt.Columns.Add(column); row[name] = pi.GetValue(t, null); } } dt.Rows.Add(row); } ds.Tables.Add(dt); return ds.Tables[0]; }
4.合并相同的DataTable：
public static DataTable MergeSameDatatable(DataTable dataTable1, DataTable dataTable2)
{
var newDataTable = dataTable1.Clone();
var obj = new object[newDataTable.Columns.Count];
for (var i = 0; i < dataTable1.Rows.Count; i++)
{
dataTable1.Rows[i].ItemArray.CopyTo(obj, 0);
newDataTable.Rows.Add(obj);
}
for (var i = 0; i < dataTable2.Rows.Count; i++)
{
dataTable2.Rows[i].ItemArray.CopyTo(obj, 0);
newDataTable.Rows.Add(obj);
}
return new DataTable();
}5.将两个列不同的DataTable合并成一个新的DataTable ：
public static DataTable UniteDataTable(DataTable dt1, DataTable dt2, string dtName)
{
var dt3 = dt1.Clone();
for (var i = 0; i < dt2.Columns.Count; i++)
{
dt3.Columns.Add(dt2.Columns[i].ColumnName);
}
var obj = new object[dt3.Columns.Count];
for (int i = 0; i < dt1.Rows.Count; i++)
{
dt1.Rows[i].ItemArray.CopyTo(obj, 0);
dt3.Rows.Add(obj);
}
if (dt1.Rows.Count >= dt2.Rows.Count)
{
for (var i = 0; i < dt2.Rows.Count; i++)
{
for (var j = 0; j < dt2.Columns.Count; j++)
{
dt3.Rows[i][j + dt1.Columns.Count] = dt2.Rows[i][j].ToString();
}
}
}
else
{
for (var i = 0; i < dt2.Rows.Count - dt1.Rows.Count; i++)
{
var dr3 = dt3.NewRow();
dt3.Rows.Add(dr3);
}
for (var i = 0; i < dt2.Rows.Count; i++)
{
for (var j = 0; j < dt2.Columns.Count; j++)
{
dt3.Rows[i][j + dt1.Columns.Count] = dt2.Rows[i][j].ToString();
}
}
}
dt3.TableName = dtName;
return dt3;
}6.Datatable 转 List
