Proc SQL how to use SET FROM statement correctly

[weg]

I inherited a program with an existing querry that works by continually applying changes to a temp table in proc sql  but generates warning messages.  Here is the simplest part of that process:

proc sql;

...

create table tempds as
select a.*,b.wantedcol
from tempds as a, othertable as b
where a.fkey1=b.sfkey1 and a.key2=b.key2;
quit;

an example of the warning:
WARNING: This CREATE TABLE statement recursively references the target table. A consequence of this is a possible data integrity
problem.

I want to fix this and stay within proc sql even though I could handle this specific example in a data step since I have more sql querries to fix.

This is my attempt to fix, but I am doing something wrong between the SET statement and the FROM statement. I'm sure there is some slight syntax change I need but I cant figure out what needs updating

PROC SQL;

...
ALTER TABLE tempds
ADD wantedcol num(3);

UPDATE tempds
SET wantedcol=b.wantedcol
FROM tempds a join othertable b
WHERE a.fkey=b.sfkey and a.key2=b.key2;
quit;

The error is the following  at the FROM keyword:
ERROR 22-322: Syntax error, expecting one of the following: ;, !!, *, **, +, ',', -, /, WHERE, ||.

This is sas 9.4.

I'm using these 2 links as reference, and maybe sas's sql syntax is a bit different for the FROM keyword:

https://documentation.sas.com/doc/en/vdmmlcdc/8.1/sqlproc/n1hz0uhw57yye2n16m5r103jjpjj.htm

https://learn.microsoft.com/en-us/answers/questions/1166695/add-column-to-table-and-populate-from-an...

Thanks,

[Ksharp]

Because the created table name is the same as the input table,.

You could use option UNDOPOLICY=NONE to suppress this kind of warning info.

proc sql  undopolicy=none ;
..............

[Tom · Accepted solution]

Put a SUBQUERY after the = that returns only one value.

Example:

data have;
  set sashelp.class;
run;
data other;
  set sashelp.class(obs=5);
  keep name sex ;
  rename sex=gender;
run;
proc sql;
alter table have add gender char(1);
update have a
  set gender=(
  select b.gender from other b
  where b.name = a.name
  )
  where name in (select name from other)
;
quit;
proc print;
run;