topic Merge Operation in SAS Programming

Merge Operation

Kishore_01 — Wed, 29 Feb 2012 05:51:35 GMT

proc sort data=dataset1;

by ID;

run;

proc sort data=dataset2;

by ID;

run;

data dataset2;

merge dataset2 (in=a)

dataset1 (in=b);

by ID;

if a;

run;

Is this overwriting the existing dataset2, and applying the merge operation ?

Re: Merge Operation

manojinpec — Wed, 29 Feb 2012 06:27:27 GMT

It is doing left join on data

Merge Operation

sas_Forum — Wed, 29 Feb 2012 07:12:52 GMT

According to your code it will overwrite the dataset2 and keep the variables and of data in variable ID if existing in both datasets or if not existing in dataset1 and keep osb existing in dataset2

Re: Merge Operation

LinusH — Wed, 29 Feb 2012 07:13:16 GMT

Yes

Re: Merge Operation

Vish33 — Wed, 29 Feb 2012 07:15:19 GMT

yeah..its going to overwrite the data with maching BY variable's and lefts the remaining in dataset 2.

in simple term LEFT JOIN

Re: Merge Operation

Haikuo — Wed, 29 Feb 2012 12:52:28 GMT

Vish33 and manojinpec,

If the 'LEFT JOIN' you mentioned is the SQL LEFT JOIN, then you were wrong. SQL LEFT JOIN will keep the value of first table instead.

Regards,

Haikuo

Re: Merge Operation

Patrick — Wed, 29 Feb 2012 13:45:48 GMT

Yes, the source dataset2 (the one in the merge statement) will be replaced by the same named target data set (the one in the data statement) in case the data step finishes without errors.

A SAS merge is not the same like a SQL join because a SAS merge statement behaves differently to a SQL join in case of many-to-many relationships.

Re: Merge Operation

Vish33 — Wed, 29 Feb 2012 14:58:17 GMT

Haikuo,

Thanks for info...that was a blind mistake of mine..:)