Naming columns using values from data table

Question

Let's say I have two columns A and B.

A     B
12    "randstr"
39    "randstr"
2     "randstr"

This random string is repeated in each row.

I'm interested in how I can get the table below:

randstr     B
12          "randstr"
39          "randstr"
2           "randstr"

The value in the column B was used to rename column A. I have tried using rename and all sorts of macro magic but failed. I have no idea how to proceed.

I've tried the answers below and they just don't allow for reading the value from the data and then using the value as a column name:

1. https://communities.sas.com/t5/General-SAS-Programming/dates-used-as-column-names/td-p/168803
2. https://stats.idre.ucla.edu/sas/code/a-few-sas-macro-programs-for-renaming-variables-dynamically/
3. SAS - Dynamically create column names using the values from another column
4. Renaming Column with Dynamic Name

Answer 1

The transformation could also be seen as a row-wise transposition.

data have;
attrib A length=8 B length=$32;
row+1;
input
A   & B; datalines;
12    xyz-123-abc
39    xyz-123-abc
2     xyz-123-abc
run;

proc transpose data=have out=want(drop=row _name_);
  by row;
  var A;
  id B;
  copy B;
run;

In non-toy scenarios the B column is often not a single value. Try the same transpose with data having variation in B. The procedure will create two new columns from the values of B.

A   & B; datalines;
12    xyz-123-abc
39    xyz-123-abc
2     xyz-123-abc
3141  xyz-456-def

Answer 2

Using this macro, it's fairly straightforward:

/* get first value in the dataset */
%let new_col=%mf_getvalue(work.YOURDATA,B);

/* rename variable A */
proc datasets library=work nolist;
 modify YOURDATA;
 rename A=%sysfunc(dequote(&new_col));
quit;