Removing duplicate records in a file based on single column explanation Post: 302608637

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Top Forums Shell Programming and Scripting Removing duplicate records in a file based on single column explanation Post 302608637 by Scrutinizer on Sunday 18th of March 2012 06:42:21 AM

03-18-2012

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The purpose is to go over the same file twice, first to find the number of occurrence of field one. The second time only to print lines of which field 1 occurs exactly once..

-F,	Set the input field separator to comma
NR==FNR	When the first file is being read (only then are FNR and NR equal)
C[$1]++	create an (associative) array element with the first filed as the index and increment its value by 1
next	start reading the next record
C[$1]==1	(while reading the second file, which in this case is the first file for the second time) if the count is equal to 1, i.e. the total number of appearances of field 1 in the input file is 1 then print the record (line).
infile infile	read infile followed by infile

The same can be done without arrays and with only a single pass, but than the input file needs to be sorted on field 1:

Code:

awk -F, '$1!=p{if(q)print q; q=$0; p=$1; next}{q=x} END{if(q)print q}' infile

Last edited by Scrutinizer; 03-18-2012 at 07:48 AM..

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db2_field_precision

DB2_FIELD_PRECISION(3)							 1						    DB2_FIELD_PRECISION(3)

db2_field_precision - Returns the precision of the indicated column in a result set

SYNOPSIS

       int db2_field_precision (resource  $stmt, mixed	$column)

DESCRIPTION

	Returns the precision of the indicated column in a result set.

PARAMETERS

	      o $stmt
		- Specifies a statement resource containing a result set.

	      o $column
		-  Specifies  the  column in the result set. This can either be an integer representing the 0-indexed position of the column, or a
		string containing the name of the column.

RETURN VALUES

	Returns an integer containing the precision of the specified  column.  If  the	specified  column  does  not  exist  in  the  result  set,
       db2_field_precision(3) returns FALSE.

SEE ALSO

       db2_field_display_size(3), db2_field_name(3), db2_field_num(3), db2_field_scale(3), db2_field_type(3), db2_field_width(3).

PHP Documentation Group 												    DB2_FIELD_PRECISION(3)