data AtBats; input Player $11. atbats; datalines; Walker 271 Wingo 240 Thomas 231 Marzilli 220 Beary 211 Morales 249 Mooney 254 Williams 209 Bradley Jr. 162 ; run; data Playerposition; input Player $11. Position $ ; datalines; Marzilli Outfield Williams Outfield Bradley Jr. Outfield Wingo Infield Walker Infield Thomas Infield Beary Infield Morales Infield Mooney Infield ; run; *Original correlated subquery; proc sql; select player, atbats from atbats where "Infield"= (select position from playerposition where atbats.player=playerposition.player); quit; *Correlation error; proc sql; select player, atbats from atbats where "Infield"= (select position from playerposition where atbats.player=position.player); quit; *SAS resolves ambiguity; proc sql; select player, atbats from atbats where "Infield"= (select position from playerposition where atbats.player=player); quit; *SAS resolves ambiguity; proc sql; select atbats from atbats where "Infield"= (select position from playerposition where atbats.player=player); quit;