b<-data.frame(a1=sqldf("select V238-v091 as a1 from a where v003=1 and v002='A'"),b1=sqldf("select V238-v091 as b1 from a where v003=1 and v002='B'"),a2=sqldf("select V238-v091 as a2 from a where v003=2 and v002='A'"),b2=sqldf("select V238-v091 as b2 from a where v003=2 and v002='B'"),a3=sqldf("select V238-v091 as a3 from a where v003=3 and v002='A'"),b3=sqldf("select V238-v091 as b3 from a where v003=3 and v002='B'"),a4=sqldf("select V238-v091 as a4 from a where v003=4 and v002='A'"),b4=sqldf("select V238-v091 as b4 from a where v003=4 and v002='B'"))
Error in data.frame(a1 = sqldf("select V238-v091 as a1 from a where v003=1 and v002='A'"),  :
  参数值意味着不同的行数: 18, 9, 17