awk script to perform an action similar to vlookup between two csv files in UNIX

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# 1  
Old 09-03-2014
awk script to perform an action similar to vlookup between two csv files in UNIX


I am new to awk/unix and am trying to put together an awk script to perform an action similar to vlookup between the two csv files.

Here are the contents of the two files:

File 1:


File 2:


I am trying to do a lookup between the two files based on the date and the parent ID. If the date AND The parent ID are the same, the "ID" (first column from in file 2) needs to be copied to file 1 (as the first column). If they are not the same, then a blank should be copied to file 1.

For example, the output would be as follows:

File 1:


Can someone please assist?

Really appreciate any help!

Thank you,
# 2  
Old 09-03-2014
Yes, what have you wrote so far?
# 3  
Old 09-03-2014
code so far

I tried to do something like this:

awk -F, 'FNR==NR{a[$2]=$1;next}$1 in a {$7=a[$1]}1' OFS="," FS="," file2.csv file1.csv

The output is completely wrong though Smilie

Have not written any awk scripts before and not sure how I could fix my code..
# 4  
Old 09-03-2014
this should work, not if your headings matched in file 2 the hard-coded assign of ID would not be required:

awk -F, 'FNR==NR{a[$2,$3]=$1;next}
  if($1 SUBSEP $2 in a) $1=a[$1,$2] OFS $1
  else $1=OFS $1
  if(FNR==1) $1="ID"
}1' OFS="," file2.csv file1.csv

# 5  
Old 09-03-2014
Another approach:
awk -F, 'NR==FNR {a[$2,$3]=$1; next} FNR==1 {$1="ID" FS $1} a[$1,$2] {$1=a[$1,$2] FS $1}1' OFS=, file2 file1

Last edited by Franklin52; 09-03-2014 at 06:21 PM..
# 6  
Old 09-03-2014
@Franklin52 - I considered that approach as well, however it doesn't put blank entry in field #1 when lookup fails:

If they are not the same, then a blank should be copied to file 1.
This User Gave Thanks to Chubler_XL For This Post:
# 7  
Old 09-03-2014
@Franklin52 and @Chubler_XL thanks for your replies!

File 1 currently does not have a ID column. This ID column has to be inserted. @Franklin52, when I try tried your approach, the outout is exactly file1 without the ID column inserted?

@Chubler_XL, when I try your approach, the output is as follows:


Am i missing anything?

Thanks again guys!
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