May be used

Using system;
Using system. Collections. Generic;
Using system. LINQ;
Using system. text;
Using system. Text. regularexpressions;

Namespace consoleapplication21
{
Public interface ifiltergroupsql
{
String setgroupjoinsql (string SQL );
}

Public class countpartyunion: ifiltergroupsql
{
Public String setgroupjoinsql (string SQL)
{
SQL + = "countpartyunionsql union ";
Return SQL;
}
}

Public class businessunitunion: ifiltergroupsql
{
Public String setgroupjoinsql (string SQL)
{
SQL + = "businessunitsql union ";
Return SQL;
}
}
Public class businessunitunion1: ifiltergroupsql
{
Public String setgroupjoinsql (string SQL)
{
SQL + = "businessunitsql1 union ";
Return SQL;
}
}
Public class traderunion: ifiltergroupsql
{
Public String setgroupjoinsql (string SQL)
{

SQL + = "traderunionsql union ";
Return SQL;
}
}
Public class traderunion1: ifiltergroupsql
{
Public String setgroupjoinsql (string SQL)
{

SQL + = "traderunionsql1 union ";
Return SQL;
}
}

Public class filtergroupchain
{
Public ilist <ifiltergroupsql> filterchains = new list <ifiltergroupsql> ();

Public filtergroupchain addfiltergroupchain (ifiltergroupsql filter)
{
Filterchains. Add (filter );
Return this;
}

Public String setgroupjoinsql ()
{
String S = string. empty;
List <string> strlist = new list <string> ();

Foreach (var f in filterchains)
{
S = f. setgroupjoinsql (s );
}
S = RegEx. Replace (S, @ "(\ W *) (Union \ s) $", replacemethod );
Return S;
}

Private string replacemethod (match)
{
String S = "";

S = match. Groups [1]. tostring ();

Return S;
}
}
;
Class Program
{
Static void main (string [] ARGs)
{

Filtergroupchain = new filtergroupchain ();

Filtergroupchain. addfiltergroupchain (New countpartyunion ())
. Addfiltergroupchain (New businessunitunion ())
. Addfiltergroupchain (New traderunion ())
. Addfiltergroupchain (New traderunion1 ())
. Addfiltergroupchain (New businessunitunion1 ());
String S = filtergroupchain. setgroupjoinsql ();
Console. writeline (s );

Console. Read ();
}
}
}

May be used