Need help regards Generate query to display Grid

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C#

ASP.NET

SQL-Server

Gridview

Following are my tables

PartyMaster - PId PK Identity | PName varchar

ItemMaster - ItemId PK identity | ItemCode varchar unique | ItemName varchar

ItemVendorMaster - ItemVendorId PK Identity | ItemId FK(ItemMaster-ItemId) | PartyId FK(PartyMaster-PId) | Percent double


Now I want to show the above 'ItemVendorMaster' details in gridview asp.net as follows

ItemId | ItemCode | ItemName | Party1 | %1 | Party2 | %2 | Party3 | %3
1      | 1	 | PC	    | ddl(P1)|50  | ddl(P2)| 50 | ddl(NS)  |  
2      | 2	 | CPU	    | ddl(P2)|70  | ddl(P4)|20  |ddl(P8) |10

ddl - Drop Down List
NS - Not Selected(Blank)
But the data in table 'ItemVendorMaster' is like as follow

ItemVendorId | ItemId | PartyId | Percent
1	     | 1      | 1       | 50
2	     | 1      | 2       | 50
3	     | 2      | 2       | 70
4	     | 2      | 4       | 20
5	     | 2      | 8       | 10

How can I show above grid, I am not getting sql query for it, Please Help
Note:
In grid same row must not have same name selected from dropdown
Sum of all % in same row in grid must be 100%