private class FieldInfo
{
public string RelationName;
public string FieldName; //source table field name
public string FieldAlias; //destination table field name
public string Aggregate;
}
private void ParseFieldList(string FieldList, bool AllowRelation)
{
/*
* This code parses FieldList into FieldInfo objects and then
* adds them to the m_FieldInfo private member
*
* FieldList systax: [relationname.]fieldname[ alias], ...
*/
if (m_FieldList == FieldList) return;
m_FieldInfo = new System.Collections.ArrayList();
m_FieldList = FieldList;
FieldInfo Field; string[] FieldParts;
string[] Fields=FieldList.Split(',');
int i;
for (i=0; i<=Fields.Length-1; i++)
{
Field=new FieldInfo();
//parse FieldAlias
FieldParts = Fields[i].Trim().Split(' ');
switch (FieldParts.Length)
{
case 1:
//to be set at the end of the loop
break;
case 2:
Field.FieldAlias=FieldParts[1];
break;
default:
throw new Exception("Too many spaces in field definition: '" + Fields[i] + "'.");
}
//parse FieldName and RelationName
FieldParts = FieldParts[0].Split('.');
switch (FieldParts.Length)
{
case 1:
Field.FieldName=FieldParts[0];
break;
case 2:
if (AllowRelation==false)
throw new Exception("Relation specifiers not permitted in field list: '" + Fields[i] + "'.");
Field.RelationName = FieldParts[0].Trim();
Field.FieldName=FieldParts[1].Trim();
break;
default:
throw new Exception("Invalid field definition: " + Fields[i] + "'.");
}
if (Field.FieldAlias==null)
Field.FieldAlias = Field.FieldName;
m_FieldInfo.Add (Field);
}
}
public DataTable CreateJoinTable(string TableName, DataTable SourceTable, string FieldList)
{
/*
* Creates a table based on fields of another table and related parent tables
*
* FieldList syntax: [relationname.]fieldname[ alias][,[relationname.]fieldname[ alias]]...
*/
if (FieldList==null)
{
throw new ArgumentException("You must specify at least one field in the field list.");
//return CreateTable(TableName, SourceTable);
}
else
{
DataTable dt = new DataTable(TableName);
ParseFieldList(FieldList, true);
foreach(FieldInfo Field in m_FieldInfo)
{
if(Field.RelationName==null)
{
DataColumn dc = SourceTable.Columns[Field.FieldName];
dt.Columns.Add(dc.ColumnName, dc.DataType, dc.Expression);
}
else
{
DataColumn dc = SourceTable.ParentRelations[Field.RelationName].ParentTable.Columns[Field.FieldName];
dt.Columns.Add(dc.ColumnName, dc.DataType, dc.Expression);
}
}
if (ds!=null)
ds.Tables.Add(dt);
return dt;
}
}
public void InsertJoinInto(DataTable DestTable, DataTable SourceTable,
string FieldList, string RowFilter, string Sort)
{
/*
* Copies the selected rows and columns from SourceTable and inserts them into DestTable
* FieldList has same format as CreatejoinTable
*/
if (FieldList==null)
{
throw new ArgumentException("You must specify at least one field in the field list.");
//InsertInto(DestTable, SourceTable, RowFilter, Sort);
}
else
{
ParseFieldList(FieldList, true);
DataRow[] Rows = SourceTable.Select(RowFilter, Sort);
foreach(DataRow SourceRow in Rows)
{
DataRow DestRow = DestTable.NewRow();
foreach(FieldInfo Field in m_FieldInfo)
{
if(Field.RelationName==null)
{
DestRow[Field.FieldName] = SourceRow[Field.FieldName];
}
else
{
DataRow ParentRow = SourceRow.GetParentRow(Field.RelationName);
DestRow[Field.FieldName] = ParentRow[Field.FieldName];
}
}
DestTable.Rows.Add(DestRow);
}
}
}
public DataTable SelectJoinInto(string TableName, DataTable SourceTable, string FieldList, string RowFilter, string Sort)
{
/*
* Selects sorted, filtered values from one DataTable to another.
* Allows you to specify relationname.fieldname in the FieldList to include fields from
* a parent table. The Sort and Filter only apply to the base table and not to related tables.
*/
DataTable dt = CreateJoinTable(TableName, SourceTable, FieldList);
InsertJoinInto(dt, SourceTable, FieldList, RowFilter, Sort);
return dt;
}
测试应用程序
保存，然后编译 DataSetHelper 类在上一节中创建的。
请按照下列步骤创建一个新 Visual C# Windows 应用程序：
启动 Visual Studio.net。
在 文件 菜单上指向 新建，然后单击 项目。
在 新建项目 对话框中单击在 项目类型，Visual C# 项目，然后单击 模板 下的 Windows 应用程序。
if (FieldList==null)
{
throw new ArgumentException("You must specify at least one field in the field list.");
//return CreateTable(TableName, SourceTable);
}
-并且-
if (FieldList==null)
{
throw new ArgumentException("You must specify at least one field in the field list.");
//InsertInto(DestTable, SourceTable, RowFilter, Sort);
}
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