-- Database schema
| height_info : height_id [ INTEGER ] primary_key , height_in_cm [ INTEGER ] , height_in_inch [ TEXT ] | weight_info : weight_id [ INTEGER ] primary_key , weight_in_kg [ INTEGER ] , weight_in_lbs [ INTEGER ] | PlayerInfo : ELITEID [ INTEGER ] primary_key , PlayerName [ TEXT ] , birthdate [ TEXT ] , birthyear [ DATE ] , birthmonth [ INTEGER ] , birthday [ INTEGER ] , birthplace [ TEXT ] , nation [ TEXT ] , height [ INTEGER ] PlayerInfo.height = height_info.height_id , weight [ INTEGER ] PlayerInfo.weight = weight_info.weight_id , position_info [ TEXT ] , shoots [ TEXT ] , draftyear [ INTEGER ] , draftround [ INTEGER ] , overall [ INTEGER ] , overallby [ TEXT ] , CSS_rank [ INTEGER ] , sum_7yr_GP [ INTEGER ] , sum_7yr_TOI [ INTEGER ] , GP_greater_than_0 [ TEXT ] | SeasonStatus : ELITEID [ INTEGER ] SeasonStatus.ELITEID = PlayerInfo.ELITEID , SEASON [ TEXT ] , TEAM [ TEXT ] , LEAGUE [ TEXT ] , GAMETYPE [ TEXT ] , GP [ INTEGER ] , G [ INTEGER ] , A [ INTEGER ] , P [ INTEGER ] , PIM [ INTEGER ] , PLUSMINUS [ INTEGER ] |
-- -- How many players, who were drafted by Anaheim Ducks in 2008, have played for U.S. National U18 Team?

SELECT COUNT(DISTINCT T1.ELITEID) FROM PlayerInfo AS T1 INNER JOIN SeasonStatus AS T2 ON T1.ELITEID = T2.ELITEID WHERE T1.overallby = 'Anaheim Ducks' AND T1.draftyear = 2008 AND T2.TEAM = 'U.S. National U18 Team';