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public class DataTableHelper
{
/// <summary>
/// dt分页
/// </summary>
/// <param name="dt">记录集 DataTable</param>
/// <param name="PageIndex">当前页</param>
/// <param name="pagesize">一页的记录数</param>
/// <returns></returns>
public static DataTable SplitDataTable(DataTable dt, int PageIndex, int PageSize)
{
if (dt == null)
{
return null;
}
if (PageIndex == 0)
return dt;
DataTable newdt = dt.Clone();
//newdt.Clear();
int rowbegin = (PageIndex - 1) * PageSize;
int rowend = PageIndex * PageSize;
if (rowbegin >= dt.Rows.Count)
return newdt;
if (rowend > dt.Rows.Count)
rowend = dt.Rows.Count;
for (int i = rowbegin; i <= rowend - 1; i++)
{
DataRow newdr = newdt.NewRow();
DataRow dr = dt.Rows[i];
foreach (DataColumn column in dt.Columns)
{
newdr[column.ColumnName] = dr[column.ColumnName];
}
newdt.Rows.Add(newdr);
}
return newdt;
}
/// <summary>
/// 合并两结构不同的dt（两表列名不能相同）
/// </summary>
/// <param name="udt1">左表</param>
/// <param name="udt2">右表</param>
/// <returns></returns>
public static DataTable UniteDataTable(DataTable udt1, DataTable udt2)
{
DataTable udt3 = udt1.Clone();
int row1 = udt1.Rows.Count;
int row2 = udt2.Rows.Count;
int colum1 = udt1.Columns.Count;
int colum2 = udt2.Columns.Count;
int colum3 = udt3.Columns.Count;
for (int i = 0; i < colum2; i++)
{
udt3.Columns.Add(udt2.Columns[i].ColumnName);
}
object[] obj = new object[colum3];
for (int i = 0; i < row1; i++)
{
udt1.Rows[i].ItemArray.CopyTo(obj, 0);
udt3.Rows.Add(obj);
}
if (row1 >= row2)
{
for (int i = 0; i < row2; i++)
{
DataRow dataRow2 = udt2.Rows[i];
DataRow dataRow3 = udt3.Rows[i];
for (int j = 0; j < colum2; j++)
{
dataRow3[j + colum1] = dataRow2[j].ToString();
}
}
}
else
{
DataRow dr3;
for (int i = 0; i < row2 - row1; i++)
{
dr3 = udt3.NewRow();
udt3.Rows.Add(dr3);
}
for (int i = 0; i < row2; i++)
{
for (int j = 0; j < colum2; j++)
{
udt3.Rows[i][j + colum1] = udt2.Rows[i][j].ToString();
}
}
}
return udt3;
}
/// <summary>
/// 移除重复数据
/// </summary>
/// <param name="SourceDt">源表</param>
/// <param name="field">根据条件移除的字段</param>
/// <returns></returns>
public static DataTable GetDistinctSelf(DataTable SourceDt, string field)
{
int j = SourceDt.Rows.Count;
if (j > 1)
{
int k = j - 1;
int i = 0;
while (i <= k)
{
DataRow dr = SourceDt.Rows[i];
string fieldName = dr[field].ToString();
DataRow[] rows = SourceDt.Select(string.Format("{0}='{1}'", field, fieldName));
if (rows.Length > 1)
{
SourceDt.Rows.RemoveAt(i); //存在重复就移除
k = k - 1;
}
else
{
i++;
}
}
}
return SourceDt;
}
/// <summary>
/// 低效判断dt是否存在重复记录，true为存在
/// </summary>
/// <param name="dt"></param>
/// <param name="strComuns"></param>
/// <returns></returns>
public bool checkDt(DataTable dt, string[] strComuns)
{
// string[] strComuns = { "ISBN", "书名", "单价" };
DataView myDataView = new DataView(dt);
int i = myDataView.ToTable(true, strComuns).Rows.Count;
int j = dt.Rows.Count;
if (i < j)
{
return true; //存在重复记录
}
return false; //不存在重复记录
}
///
/// <summary>
/// 高效判断dt是否存在重复记录，true为存在
/// </summary>
/// <param name="dt1">源表</param>
/// <param name="strComuns">列名 string[] strComuns = { "ISBN", "书名", "单价", "进货折扣", "销售折扣", "供应商" };</param>
/// <returns>true重复，false不重复</returns>
public static bool isRepeatDt(DataTable dt1, string[] strComuns)
{
int PageIndex = 1; //当前页
int PageSize; //每页数据量
int index = PageIndex - 1; //循环次数 一次
int allCount = dt1.Rows.Count; //总数据量
if (allCount > 10)
{
PageSize = 10;
}
else
{
PageSize = allCount;
}
for (int m = index; m < PageIndex; m++)
{
DataTable splitDt = SplitDataTable(dt1, PageIndex, PageSize); //dt分页
int j = splitDt.Rows.Count; //分页后的数据量
DataView myDataView = new DataView(splitDt); //dt拷贝到视图
int i = myDataView.ToTable(true, strComuns).Rows.Count; //查重后的数据量
if (i < j) //小于则重复，大于则不重复
{
//存在重复记录,跳出循环
return true;
}
else
{
if (PageSize == j)
{
PageIndex++;
index = PageIndex - 1;
}
else
{
//循环到尾行,跳出循环
return false;
}
}
}
return true;
}
/// <summary>
/// Json 字符串 转换为 DataTable数据集合
/// </summary>
/// <param name="json"></param>
/// <returns></returns>
public static DataTable jsonToDt(string json)
{
DataTable dataTable = new DataTable(); //实例化
DataTable result;
try
{
JavaScriptSerializer javaScriptSerializer = new JavaScriptSerializer();
javaScriptSerializer.MaxJsonLength = Int32.MaxValue; //取得最大数值
ArrayList arrayList = javaScriptSerializer.Deserialize<ArrayList>(json);
if (arrayList.Count > 0)
{
foreach (Dictionary<string, object> dictionary in arrayList)
{
if (dictionary.Keys.Count<string>() == 0)
{
result = dataTable;
return result;
}
//Columns
if (dataTable.Columns.Count == 0)
{
foreach (string current in dictionary.Keys)
{
dataTable.Columns.Add(current, dictionary[current].GetType());
}
}
//Rows
DataRow dataRow = dataTable.NewRow();
foreach (string current in dictionary.Keys)
{
dataRow[current] = dictionary[current];
}
dataTable.Rows.Add(dataRow); //循环添加行到DataTable中
}
}
}
catch
{
}
result = dataTable;
return result;
}
}
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