Check for null values in a column


 
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# 1  
Old 04-03-2009
Data Check for null values in a column

Hi All,

I have a file with 10 columns and get the required data for nine columns properly except 8th. In 8th column i have both NULL and NON NULL values...i.e
certain records have values for all the columns including 8th column and certain records have 8th column as NULL.My requisite is,without opening or reading the file line by line i need to check if the file contains atleast one NULL value for 8th column .If NULL value exists then i need to reject the file else process the file.

for eg if my file contains records like this,

1,2,3,4,5,6,7,8,9,10
a,s,d,f,f,g,h,,k,l
aa,ss,bb,ee,ff,gg,bb,,kk,ii

how do i get my job done??
Thanks in Advance

Last edited by ganesh_248; 04-03-2009 at 09:53 AM..
# 2  
Old 04-03-2009
Does something like this work for you?
Code:
 nawk 'FS="," {if ($8 == "") print "Line", NR, "REJECTED" }' file

HTH,
n.
# 3  
Old 04-03-2009
Quote:
Originally Posted by nephros
Does something like this work for you?
Code:
 nawk 'FS="," {if ($8 == "") print "Line", NR, "REJECTED" }' file

HTH,
n.
Have you tried this solution?
# 4  
Old 04-03-2009
Quote:
Originally Posted by vgersh99
Have you tried this solution?
Uhm, yes, works here with the input data from the OP.
# 5  
Old 04-03-2009
Quote:
Originally Posted by nephros
Uhm, yes, works here with the input data from the OP.
Code:
nawk -F, '{if ($8 == "") print "Line", NR, "REJECTED" }' file

# 6  
Old 04-03-2009
Quote:
Originally Posted by vgersh99
Code:
nawk -F, '{if ($8 == "") print "Line", NR, "REJECTED" }' file

Which does the exact same thing unless I'm missing something.
(I do admit that
Code:
 nawk 'BEGIN { FS="," } {foo}'

would have been better.)

Anyway it's a matter of taste, I prefer to set FS inside the script because it's a bit more flexible wrt more complex separators. But it really does not matter for the CSV above.

EDIT: I stand corrected. Behaviour of my original version is highly dependant on the awk implementation used. I works in /usr/bin/nawk from Solaris 10.
Just checked with The One True awk, and my original version does not work there. vgersh99s version and the BEGIN block variation do.

Last edited by nephros; 04-03-2009 at 12:02 PM..
# 7  
Old 04-03-2009
Quote:
Originally Posted by nephros
Which does the exact same thing unless I'm missing something.
(I do admit that
Code:
 nawk 'BEGIN { FS=":" } {foo}'

would have been better.)

Anyway it's a matter of taste, I prefer to set FS inside the script because it's a bit more flexible wrt more complex seperators. But it really does not matter for the CSV above.
You are missing something...Smilie
The FS is changed after the line is read, so it doesn't affect the FS in the current line in the buffer. Your solution gives all the lines of the data from the OP. To get the proper output you have to rearrange the buffer with $0=$0:

Code:
nawk '{FS=",";$0=$0;if ($8 == "") print "Line", NR, "REJECTED" }' file

Regards
 
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