Populate SAS macro-variable using a SQL statement within another SQL statement? - sas

Question

I stumbled upon the following code snippet in which the variable top3 has to be filled from a table have rather than from an array of numbers.
%let top3 = 14 15 42; /* This should be made obsolete.. */
%let no = 3;
proc sql;
create table want as
select *
from (select x, y from foo) a
%do i = 1 %to &no.;
%let current = %scan(&top3.,&i.); /* What do I need to put here? */
left join (select x, y from bar where z=&current.) row_&current.
on a.x = row_&current..x
%end;
;
quit;
The table have contains the xs from the string and looks as follows:
i x
1 14
2 15
3 42
I am now wondering how I should modify the %let current = ... line such that current is populated from the table have. I know how to populate a macro variable using proc sql with select .. into, but I am afraid that the way I am going right now is fully against SAS philosophy.

Answer 1

It looks like you're more or less transposing something. If that's the case, this is doable in macro/sql pretty easily.
First, here's the simple version - no macro.
proc sql;
create table class_t as
select * from (
select name from sashelp.class ) class
left join (
select name, age as age_Alfred
from sashelp.class
where name='Alfred') Alfred
on class.name = Alfred.name
;
quit;
We grab the value of age from the Alfred row and put it on the main join. This isn't exactly what you're doing, but it seems similar. (I'm just using one table, but you can of course use two here.)
Now, how do we extend this to be table-driven and not handwritten? Macros!
First, here's the macro - just taking the Alfred bit and making it generic.
%macro joiner(name=);
left join (
select name, age as age_&name.
from sashelp.class
where name="&name.") &name.
on class.name = &name..name
%mend joiner;
Second, we look at this and see two things we need to put into macro lists: the SELECT variable list (we'll get one new variable for each call), and the JOIN list.
proc sql;
select cats('%joiner(name=',name,')')
into :joinlist separated by ' '
from sashelp.class;
select cats(name,'.age_',name)
into :selectlist separated by ','
from sashelp.class;
quit;
And then, we just call it!
proc sql;
create table class_t as
select class.name,&selectlist. from (
select name from sashelp.class) class
&joinlist.
;
quit;
Now, your dataset you call the macro lists from is perhaps the dataset with the 3 rows in it you have above ("have"). The dataset you actually get the appending data from is some other dataset ("bar"), right? And then the ones you join to is perhaps a third dataset ("foo"). Here I just use the one, for simplicity, but the concept is the same, just different sources.

Answer 2

When the lookup data is in a table you can perform a three way join without any need for SAS Macro. You don't provide any data so the example will mock some.
Example:
Suppose a master record has several associated detail records, and the detail records contain a z value used for selection into a result set per a wanted z lookup table.
data masters;
call streaminit(2020);
do id = 1 to 100;
do x = 1 to 100;
m_rownum + 1;
code = rand('integer', 10,45);
output;
end;
end;
run;
data details;
call streaminit(2020);
do date = 1 to 20;
do x = 1 to 100;
do rep = 1 to 5;
d_rownum + 1;
amount = rand('integer', 100,200);
z = rand('integer', 10,45);
output;
end;
end;
end;
run;
data zs;
input z ##; datalines;
14 15 42
;
proc sql;
create table want as
select
m_rownum
, d_rownum
, masters.id
, masters.x
, masters.code
, details.z
, details.date
, details.amount
from
masters
left join
details
on
details.x = masters.x
inner join
zs
on
zs.z = details.z
order by
masters.id, masters.x, details.z, details.date
;
quit;