Debugging a DATA Step (5)

Understanding DATA Step Processing

Debugging a DATA Step

Incorrectly identifying a variable's type is another common execution-time error. As you know, the values for IDnum are character values. Suppose you forget to place the dollar sign ($) after the variable's name in your INPUT statement. This is not a compile-time error because SAS software cannot verify IDnum 's type until the data values for IDnum are read.

     data perm.update;
        infile invent;
        input Item $ 1-13 IDnum 15-19
              InStock 21-22 BackOrd 24-25;
        Total=instock+backord; 
     run;

Raw Data File Invent

1---+----10---+----20---+-

Bird Feeder   LG088  3 20

6 Glass Mugs  SB082  6 12

Glass Tray    BQ049 12  6

Padded Hangrs MN256 15 20

Jewelry Box   AJ498 23  0

Red Apron     AQ072  9 12

Crystal Vase  AQ672 27  0

Picnic Basket LS930 21  0

Brass Clock   AN910  2 10

1---+----10---+----20---+-
Bird Feeder LG088 3 20
6 Glass Mugs SB082 6 12
Glass Tray BQ049 12 6
Padded Hangrs MN256 15 20
Jewelry Box AJ498 23 0
Red Apron AQ072 9 12
Crystal Vase AQ672 27 0
Picnic Basket LS930 21 0
Brass Clock AN910 2 10

In this case, the DATA step completes the execution phase and the observations are written to the data set. However, several notes appear in the log.

SAS Log

NOTE: Invalid data for IDnum in line 7 15-19. RULE: ----+----1----+----2----+----3----+----4-- 07 Crystal Vase AQ672 27 0 Item=Crystal Vase IDnum=. InStock=27 BackOrd=0 Total=27 _ERROR_=1 _N_=7 NOTE: Invalid data for IDnum in line 8 15-19. 08 Picnic Basket LS930 21 0 Item=Picnic Basket IDnum=. InStock=21 BackOrd=0 Total=21 _ERROR_=1 _N_=8 NOTE: Invalid data for IDnum in line 9 15-19. 09 Brass Clock AN910 2 10 Item=Brass Clock IDnum=. InStock=2 BackOrd=10 Total=12 _ERROR_=1 _N_=9 NOTE: 9 records were read from the infile INVENT. NOTE: The data set PERM.UPDATE has 9 observations and 5 variables.

Each note identifies the location of the invalid data for each observation. In this example, the invalid data are located in columns 15-19 for all observations.