SAS : How to iterate a dataset elements within the proc sql WHERE statement? - sas

Question

I need to create multiple tables using proc sql
proc sql;
/* first city */
create table London as
select * from connection to myDatabase
(select * from mainTable
where city = 'London');
/* second city */
create table Beijing as
select * from connection to myDatabase
(select * from mainTable
where city = 'Beijing');
/* . . the same thing for other cities */
quit;
The names of those cities are in the sas table myCities
How can I embed the data step into proc sql in order to iterate through all cities ?

Answer 1

proc sql noprint;
select quote(city_varname) into :cities separated by ',' from myCities;
quit;
*This step above creates a list as a macro variable to be used with the in() operator below. EDIT: Per Joe's comment, added quote() function so that each city will go into the macro-var list within quotes, for proper referencing by in() operator below.
create table all_cities as
select * from connection to myDatabase
(select * from mainTable
where city in (&cities));
*this step is just the step you provided in your question, slightly modified to use in() with the macro-variable list defined above.

Answer 2

One relatively simple solution to this is to do this entirely in a data step. Assuming you can connect via libname (which if you can connect via connect to you probably can), let's say the libname is mydb. Using a similar construction to Max Power's for the first portion:
proc sql noprint;
select city_varname
into :citylist separated by ' '
from myCities;
select cats('%when(var=',city_varname,')')
into :whenlist separated by ' '
from myCities;
quit;
%macro when(var=);
when "&var." output &var.;
%mend when;
data &citylist.;
set mydb.mainTable;
select(city);
&whenlist.;
otherwise;
end;
run;
If you're using most of the data in mainTable, this probably wouldn't be much slower than doing it database-side, as you're moving all of the data anyway - and likely it would be faster since you only hit the database once.
Even better would be to pull this to one table (like Max shows), but this is a reasonable method if you do need to create multiple tables.

Answer 3

You need to put your proc sql code into a SAS Macro.
Create a macro-variable for City (in my example I called the macro-variable "City").
Execute the macro from a datastep program. Since the Datastep program processes one for each observation, there is no need to create complex logic to iterate.
data mycities;
infile datalines dsd;
input macrocity $ 32.;
datalines;
London
Beijing
Buenos_Aires
;
run;
%macro createtablecity(city=);
proc sql;
/* all cities */
create table &city. as
select * from connection to myDatabase
(select * from mainTable
where city = "&city.");
quit;
%mend;
data _null_;
set mycities;
city = macrocity;
call execute('%createtablecity('||city||')');
run;

Answer 4

Similar to the other solutions here really, maybe a bit simpler... Pull out a distinct list of cities, place into macros, run SQL query within a do loop.
Proc sql noprint;
Select distinct city, count(city) as c
Into :n1-:n999, :c
From connection to mydb
(Select *
From mainTable)
;
Quit;
%macro createTables;
%do a=1 %to &c;
Proc sql;
Create table &&n&a as
Select *
From connection to myDb
(Select *
From mainTable
Where city="&&n&a")
;
Quit;
%end;
%mend createTables;
%createTables;