sql "alter" new column with insert one value to all obs from another dataset

[t_ar_taat]

Hi!
I want to add new column to datasetA from another dataset(datasetB) in one step.

NOTE:
There’s no variable for merge.

From my google search,below information is hit,especially its title is so nice.

Adding One Value to All Records in a SAS® Data Set

But there’s no way for “by 1 step” or “in a data step”.

By now,I think “proc sql with alter” have possibility for it.
Or we can’t do it?

Because SAS’s help page for "alter" don’t have a example for it.

SAS help page of "alter in proc sql"

Someone please help me.
I introduce what I want to do with "2 step". 

data work.datasetB;
 var1="add this value for all obs";
 output;
run;

data work.datasetA;
 key=1;output;
 key=2;output;
 key=3;output;
run;

/* 1step */
data _null_ ;
 set datasetB;
 call symputx ('var1_value', var1) ;
 run ; 

/* 2step */
data work.datasetA;
 set work.datasetA;
 val1="&var1_value";
run;

Result

[ballardw]

proc sql;

   create table want as

   select datasetA.*, datasetB.*

   from dataset A, datasetB;

quit;

[t_ar_taat · Accepted solution]

Hi,ballardw

Thank you so much!!! so nice.

Have a nice day!