$ sqlite3 test.db
SQLite version 3.7.11 2012-03-20 11:35:50
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite>
sqlite> CREATE TABLE Table1
   ...> ("ROWID" int, "CID" varchar(2), "PID" varchar(2), "Score" int, "SortKey" int)
   ...> ;
sqlite>
sqlite> INSERT INTO Table1
   ...> ("ROWID", "CID", "PID", "Score", "SortKey")
   ...> VALUES
   ...> (1, 'C1', 'P1', 10, 1),
   ...> (2, 'C1', 'P2', 20, 2),
   ...> (3, 'C1', 'P3', 30, 3),
   ...> (4, 'C2', 'P4', 20, 3),
   ...> (5, 'C2', 'P5', 30, 2),
   ...> (6, 'C3', 'P6', 10, 1),
   ...> (7, 'C3', 'P7', 20, 2),
   ...> (8, 'C1', 'P3', 30, 4)
   ...> ;
sqlite> SELECT *
   ...> FROM table1 a
   ...> WHERE a."ROWID" IN (
   ...>     SELECT b."ROWID"
   ...>     FROM table1 b
   ...>     WHERE b."Score" >= 20
   ...>       AND b."ROWID" IS NOT NULL
   ...>       AND a."CID" = b."CID"
   ...>     ORDER BY b."CID", b."SortKey"
   ...>     LIMIT 2
   ...> )
   ...> ORDER BY a."CID", a."SortKey";
2|C1|P2|20|2
3|C1|P3|30|3
5|C2|P5|30|2
4|C2|P4|20|3
7|C3|P7|20|2