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What is the difference between nodup and nodupkey options?
 Question Submitted By :: SAS
I also faced this Question!!     Answer Posted By  
# 1
The NODUP option checks for and eliminates duplicate

The NODUPKEY option checks for and eliminates duplicate
observations by variable values.
Is This Answer Correct ?    74 Yes 10 No
# 2
The Nodup: can only remove the duplicate next to each other.
The by variables are very important for remove
the duplicates which all the variables have the same value.

The nodupkey: will remove the duplicated when they have the
same values for the by variables
Is This Answer Correct ?    30 Yes 2 No
# 3
data test1;
input id1 $ id2 $ extra ;
aa ab 3
aa ab 1
aa ab 2
aa ab 3
proc sort nodup data=test1;
by id1 ;
proc print data=test1;
output will be like this:

Obs id1 id2 extra

1 aa ab 3
2 aa ab 1
3 aa ab 2
4 aa ab 3

*nodup" is an alias for "noduprecs" which appears to
mean "no duplicate records" but there is no way sas can
know about these duplicate records unless they, by chance,
land next to each other in sequence It is a big mistake
to think sorting "nodup" will remove duplicate records.
Sometime it will, sometime it won't. The only way you can
be sure of removing duplicate records is to "proc sort
nodupkey" and include enough key variables to be sure you
will lose the duplicates you want to lose. In the case
shown above, then if we knew of the same "extra" values
being duplicates we wanted to remove then this variable
should be included in the list of sort variables and
then "nodupkey" will remove the duplicates as shown below.
proc sort nodup data=test1;
by id1 id2 extra;

proc print data=test1;
output will be like this:

Obs id1 id2 extra

1 aa ab 1
2 aa ab 2
3 aa ab 3

so as u can see nodup eliminated all duplicate observations
if you sort them by all variables but nodupkey will show
only the duplicate observation.

proc sort nodupkey data=test1;
by id1 ;
options nocenter;
proc print data=test1;
output will be like this:

Obs id1 id2 extra

1 aa ab 3
Is This Answer Correct ?    16 Yes 5 No
# 4
It deletes those observations if every variable in the
dataset has the same value

It deletes all the observation on sorting variable. It
retains the first variable and deletes all other coming
after that
Is This Answer Correct ?    13 Yes 3 No
Tariq Sharjil
# 5
Nodup : it delete the observartions based on each and every
variable value is same irespective of sorting varibale.

Nodupkey: It delete the observarions based on sorting
Is This Answer Correct ?    9 Yes 4 No
# 6
NODUP - removes the duplicates. Here the key to remove the
duplicates is the entire record.

NODUPKEY - removes the duplicates. Here the key is the
variable(s) specified by the BY statement.
Is This Answer Correct ?    5 Yes 1 No
Sas D
# 7
The nodup option in the sort procedure eliminates observations that are exactly the same across all variables.

The nodupkey option in the sort procedure eliminates observations that are exactly the same across BY variable.
Is This Answer Correct ?    4 Yes 0 No
# 8
By using the proc sort procedure along with nodup
option ,it checks for and eliminates the duplicate records.

NODUPKEY eliminates the duplicate observation keys
in the data set.
Is This Answer Correct ?    17 Yes 14 No
# 9

It checks similar BY variable values and deletes duplicate
observations in the data set based on BY variable values...


It will be available with latest version, It checks and
deletes duplicate observations in the dataset.....

Any comments plzz...
Is This Answer Correct ?    13 Yes 10 No
# 10
Nodup: Checks for duplicacy among the variables in a row and
keeps the 1st row of that observaion in the final output and
deletes the rest

Nodupkey: Checks for the duplicacy among the variables
specified in "by" statement and keeps the 1st row of the
observaion and deletes the rest
Is This Answer Correct ?    1 Yes 0 No
Shalabh Tyagi

Other SAS Interview Questions
  Question Asked @ Answers
data abc; input x y ; cards; 1 2 5 6 7 8 7 8 1 7 5 7 ; run; Proc Freq data=abc; tables x*y / chisq nopercent nocol norow PLCORR; RUN; If we run the code, we have Polychoric Correlation = 0.9054 in the last table. I want to extract this particular entry with the value. Means I will create one dataset in which this value will be stored/extracted. I need your help in coding this. Please help me out.   2
how to read raw data in sas. Do it manually and throw the programming. wns 1
How are the analysis data sets structured?   3
If you have a data set that contains 100 variables, but you need only five of those, what is the code to force SAS to use only those variable?   16
when we are using the PROC TRANSPOSE? OBSERVATIONS are repeated then what will happen and what it will show in log window.   1
what is the main difference between rename and label? (don't say that they both perform the same function). Parexel 10
what is Enterprise Guide?what is the use of it? CitiGroup 2
What data sets do you need to produce the report? Novartis 2
Can you use a macro within another macro? If so how would SAS know where the current acro ended and the new one began?   2
What is highest missing value for numeric?   1
What is difference between Global n Local Macro Variables..? TCS 6
wat is sas? is a package or programming language?   4
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