TEAM <- c("PE","PE","MPI","TDT","HPT","ATD")
CODE <- c(NA,"F","A","H","G","D")
df1 <- data.frame(TEAM,CODE)

CODE <- c(NA,"F100","A234","D664","H435","G123","A666","D345","G324",NA)
TEAM <- c(NA,NA,NA,NA,NA,NA,NA,NA,NA,NA)
df2 <- data.frame(CODE,TEAM)

CODE TEAM
1    NA   PE
2  F100   PE
3  A234  MPI
4  D664  ATD
5  H435  TDT
6  G123  HPT
7  A666  MPI
8  D345  ATD
9  G324  HPT
10   NA   PE

library(sqldf)
df2 <- sqldf(c("update df2 set TEAM =
                  case
                    when CODE like '%F%' then 'PE'
                    when CODE like '%A%' then 'MPI'
                    when CODE like '%D%' then 'ATD'
                    when CODE like '%G%' then 'HPT'
                    when CODE like '%H%' then 'TDT'
                    else 'NA'
                  end"))