Check for not null column in a pipe delimited file


 
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# 1  
Check for not null column in a pipe delimited file

Hi,

I have a requirement where I have to check whether the mandatory columns in a pipe delimited file is null and print error message.
For eg, I have to check if the 3rd,5th,6th,7th and 8th column are null and print the message "<column name> is null".
The data file will have aroung 100,000 records.
Please help!
# 2  
Hi,

Something like this:

Code:
awk -F'|' '{ 
   if( $3=="" || $5=="" || $7=="" || $8=="" ) 
         if ( $3=="" ) { print "Line ",NR, " Field 3: Mandatory field is null"; }
         if ( $5=="" ) { print "Line ",NR, " Field 5: Mandatory field is null"; }
         # ...
   else  
         do_something ; 
}' yourfile.txt


Last edited by stomp; 06-05-2016 at 08:45 AM..
This User Gave Thanks to stomp For This Post:
# 3  
Like so?
Code:
awk -F \| '{for(i=3; i<=8; i++) if(i!=4) if($i=="") printf "%s\n","column " i " is null at line " NR}' file


---
@stomp:
You cannot use !$i or for example!$3 as a test, since then the condition will also become true if the field equals 0 rather than "" (null value).

Last edited by Scrutinizer; 06-05-2016 at 08:41 AM..
These 2 Users Gave Thanks to Scrutinizer For This Post:
# 4  
Quote:
Originally Posted by Scrutinizer
You cannot use !$i or for example !$3 as a test, since then the condition will also become true if the field equals 0 rather than "" (null value).
Thanks. Changed That.
This User Gave Thanks to stomp For This Post:
# 5  
How about making it a bit more flexible? Try
Code:
awk '
NR==1   {MX = split(CHK, T, ",")
        }
        {for (i=1; i<=MX; i++)
           if ($(T[i]) == "") print "column " T[i] " is null at line " NR
        }
' FS="|" CHK="3,5,6,7,8" file
column 3 is null at line 1
column 6 is null at line 3
column 7 is null at line 6


Last edited by RudiC; 06-05-2016 at 05:48 PM.. Reason: Overlooked the "pipe" delimiter request.
This User Gave Thanks to RudiC For This Post:
# 6  
Quote:
Originally Posted by stomp
Hi,

Something like this:

Code:
awk -F'|' '{ 
   if( $3=="" || $5=="" || $7=="" || $8=="" ) 
         if ( $3=="" ) { print "Line ",NR, " Field 3: Mandatory field is null"; }
         if ( $5=="" ) { print "Line ",NR, " Field 5: Mandatory field is null"; }
         # ...
   else  
         do_something ; 
}' yourfile.txt

I think you're missing a pair a braces:
Code:
awk -F'|' '{ 
   if( $3=="" || $5=="" || $7=="" || $8=="" ) {
         if ( $3=="" ) { print "Line ",NR, " Field 3: Mandatory field is null"; }
         if ( $5=="" ) { print "Line ",NR, " Field 5: Mandatory field is null"; }
         # ...
   } else  
         do_something ; 
}' yourfile.txt

Without them, your code will execute the else clause only if the last last field tested is an empty string and, if the 1st if test does not find any empty strings, the remaining if tests will never succeed either:
Code:
awk -F'|' '{ 
   if( $3=="" || $5=="" || $7=="" || $8=="" ) { 
         if ( $3=="" ) { print "Line ",NR, " Field 3: Mandatory field is null"; }
   }
   if ( $5=="" ) { { print "Line ",NR, " Field 5: Mandatory field is null"; }
   # ...
   } else  
         do_something ; 
}' yourfile.txt

And, of course, if do_something; is more than one statement, you'll also needed braces around all statements in the else clause. The braces around your print statements don't hurt anything, but aren't strictly required since only one statement is being executed in those if then clauses.
This User Gave Thanks to Don Cragun For This Post:
# 7  
Thanks Don. Regarding awk, I'm only a newbie so far. Reading and then Try+Error. Smilie
 

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