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Merging document with proc SQL or other procedure

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Merging document with proc SQL or other procedure

[ Edited ]

Hi all,

I always merge tables with the following method which require me to sort both tables by BY field. Is there a better way where I don't have to sort the table before merging?

 

This is what I had been doing:

 

DATA Want;
MERGE have1(in=a) 2ave2(in=b);
BY common_variable;
IF a=1;
RUN;

 

Thanks,


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‎05-18-2016 12:09 PM
Super User
Posts: 3,113

Re: Merging document with proc SQL or other procedure

You could do the same thing in SQL. Behind the scenes SQL still sorts your data but you avoid having to sort it yourself. SQL isn't necessarrily better, just different:

 

proc sql;
  create table want as 
  select *
  from have1 as a
  left join have2 as b
  on a.common_variable = b.common_variable;
  ;
quit; 

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Super User
Posts: 5,092

Re: Merging document with proc SQL or other procedure

The most common replacement would be a SQL left join.  Here's a paper that talks about more variations than you might want to see:

 

http://www2.sas.com/proceedings/sugi30/249-30.pdf

 

There are other, more complex methods, including creating an index, hashing, creating a format.  But SQL would definitely the place to begin. 

 

If you are concerned about getting identical results to the MERGE, you have to consider whether any data sets might have more than one observation per value of COMMON_VARIABLE.  If both data sets might have more than one, you have to ask yourself what the result should be ... not an easy topic.

Solution
‎05-18-2016 12:09 PM
Super User
Posts: 3,113

Re: Merging document with proc SQL or other procedure

You could do the same thing in SQL. Behind the scenes SQL still sorts your data but you avoid having to sort it yourself. SQL isn't necessarrily better, just different:

 

proc sql;
  create table want as 
  select *
  from have1 as a
  left join have2 as b
  on a.common_variable = b.common_variable;
  ;
quit; 
☑ This topic is solved.

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