I am designing a generic macro to do update a table using a macro variable (say X) which is used as a column name. The problem I have is that there are ocassions where this variable X (which is used as a column name in the where clause) is null. Can someone help please
I you don't want a where clause when &X is blank, then do something like:
%if %length(&X) > 0 %then where &X = 'blahblah';
So that the where clause is only created if &X has text in it.
If &x is guaranteed to be defined but may be blank, then DWal's solution is the way to go. This is useful basically when the macro variable is a parameter, and will be defined every time the macro is run.
If it may not be defined at all, then you need to use %symexist() to check whether the macro variable is defined at all, possibly in addition to the %length check.
%macro test;
%if %symexist(X) %then %if %length(&x)>0 %then %do;
%put &=x;
%end;
%mend test;
%symdel x; *deletes x if it exists;
%test;
%let x=;
%test;
%let x=XValue;
%test;
I nest the %if to avoid an unintialized note.
Related
I am trying to solve a problem in which, based on certain conditions, it assigns you a parameter with the let function. For this exercise I am using %if with %let conditions on the code. The code I have written so far in simplified way is the following:
%let anio = 2022;
%let base = 2;
%Macro Data;
%if &anio = 2022 %then %do;
%Let year_add = %Str(&Base.C);
%Let year_add1 = %Str(&Base.B);
%mend;
%Data;
%put &=year_add;
%put &=year_add1;
The problem is that apparently the macro is not assigning any value to me in the second let statement
The first %put = &year_add gives me the correct result 2C.
Unfortunately with the second %put = &year_add1 it appears the following message: apparent symbolic referenc yeard_add1 not resolved
Can anyone can give me a hand or advise on how I can assign different let statements based on a condition?
Thanks in advance.
Your macro definition is missing an %END for the %DO.
%macro data;
%if &anio = 2022 %then %do;
%let year_add = &Base.C;
%let year_add1 = &Base.B;
%end;
%mend;
If the target macro variables, YEAR_ADD and YEAR_ADD1 do not already exist then your macro will create them as LOCAL to the DATA macro. So once the macro finishes they will be removed.
The easiest solution is just to make sure the macro variables exist before you call the macro.
%let anio = 2022;
%let base = 2;
%let year_add=;
%let year_add1=;
%data;
%put &=year_add;
%put &=year_add1;
If you are certain the macro variables do not already exist in some other macro that is calling %DATA() then you could add a %GLOBAL statement to define them in the GLOBAL macro scope so they will not be removed when the macro finishes by adding this to the macro definition:
%global year_add year_add1 ;
But that will generate an error if they have been defined as LOCAL to some other macro that called %DATA. So to be safe only force them into the GLOBAL scope if they do not already exist.
%if not %symexist(year_add) %then %global year_add;
%if not %symexist(year_add1) %then %global year_add1;
But the logic does not require you to define a macro. Just use the %IF/%THEN/%DO/%END block in open code. Then you won't have any macro variable scoping issues.
%if &anio = 2022 %then %do;
%let year_add = &Base.C;
%let year_add1 = &Base.B;
%end;
That works fine unless you are running on some really old version of SAS.
I am getting a generic 'Statement not valid or out of order' message with the below:
%macro test;
data _null_;
%if %sysfunc(fileexist("C:\report_201809.xlsx")) = 1 %then %do;
rc=%sysfunc(rename("C:\report_201809.xlsx",
"C:\report_201809.xlsx"_old.xlsx",'file'));
%end;
%mend;
%test;
The code below should get you what you need. While you can use %if statements in a data step you generally won't need to. I'm guessing the error is coming from the %sysfunc function around the fileexist and rename functions. %sysfunc allows you to call data step functions outside of a data step so it is not needed here.
%macro test;
data _null_;
if fileexist("C:\file.txt") then do;
rc = rename("C:\file.txt", "C:\file2.txt", 'file');
end;
run;
%mend;
Alternatively, you could use an X Command that allows you to execute Windows commands. You could replace the rename function with the following statement.
x move C:\file.txt C:\file2.txt;
Remove the DATA _NULL_ or proceed per #J_Lard.
Macro arguments used in %sysfunc invoked function calls are implicitly quoted and do not need additional ' or "
%macro test;
%local rc;
%if %sysfunc(fileexist(C:\report_201809.xlsx)) = 1 %then %do;
%let rc = %sysfunc(rename(C:\report_201809.xlsx,C:\report_201809_old.xlsx,file));
%end;
%test;
You original code may have worked (by way of non-obvious side effect) if the filename "C:\report_201809.xlsx"_old.xlsx" (having an extraneous ") was corrected to "C:\report_201809_old.xlsx"
I suppose symexist is used for checking macro variables (local ones). I made a test but the output is out of my expectation. The code is:
%macro test(t1,t2);
%if %symexist(t1) %then %put &t1. is exist;
%if %symexist(t2) %then %put &t2. is exist;
%mend;
%test(test1,);
The output is:
test1 is exist
is exist
Looking at the mlogic: %IF condition %symexist(t2) is TRUE.
There is no macro variable for t2. How it comes for TRUE? Anyone come explain how symexist works? I had a search but did not find.
Thanks,
Andrea
There are macro variables named T1 and T2 because you defined them by making them parameters to your macro. All macro parameters are local macro variables to the macro.
You need to use &t1 not t1 because you want to test for the existence of test1 not the existence of t1.
It will still error out though, because the macro variable t2 doesn't exist.
%let test1 = Yes;
%macro test(t1, t2);
%if %symexist(&t1) %then
%put &t1. is exist;
%if %symexist(&t2) %then
%put &t2. is exist;
%else
%put &t2. does not exist;
%mend;
%test(test1, test2);
The output will be:
test1 is exist
test2 does not exist
Could someone please explain why it is happening?
I'm trying to find objects dependencies tree in a DB.
Let's say view5 is a view sits on top view4 which sits on top view1.
Also,
view3 sits on top view2 sits on top view1.
So,
the when I query the macro for view1, I should get back view4, view5, view2 and view3.
This is the macro:
%macro dependencies(obj=);
%let dependent_objectname =;
proc sql noprint;
select "'"||trim(dependent_objectname)||"'"
into :dependent_objectname separated by ", "
from &_input.
where src_objectname in (&obj.);
quit;
%put &dependent_objectname.;
%let dependent_objectname = (&dependent_objectname.);
%put &dependent_objectname.;
%if %length("&dependent_objectname")>0 %then
%dependencies(obj = &dependent_objectname.);
%mend dependencies;
%let source = 'ditemp.depend_test1';
%put &source.;
%dependencies(obj = &source.);
First iteration works well,
I get the objects sit on top depend_test1
in a form of "('ditemp.depend_test2','ditemp.depend_test3')"
then I'm checking for the length of variable dependent_objectname (greater than zero)
and calling the macro again,
only it never stops...
I see a couple problems.
The statement:
%if %length("&dependent_objectname")>0 %then %do;
will always return true, even if the value of &dependent_objectname is null. Because the quotes are part of the value in the macro language. You probably want:
%if %length(&dependent_objectname)>0 %then %do;
That test for nullness usually works. Or see this paper for better methods. http://support.sas.com/resources/papers/proceedings09/022-2009.pdf
Before that, the statement:
%let dependent_objectname = (&dependent_objectname.);
is adding parentheses to your value. So again, even if &dependent_objectname were null, it would be () after this. It looks like you don't need these parentheses, so I would skip this statement.
I would also add:
%local dependent_objectname ;
to the top of the macro. That way each invocation of the macro will have its own local macro variable, rather than having them all use the macro variable created in the first iteration (or worse yet, all use a global macro variable).
You have sensibly added %PUT statements to help with debugging. I would expect they would show that the value of &dependent_objectname is always non-null as currently written. You could also add:
%put The length is: %length(&dependent_objectname.) ;
Since you are using an SQL query to generate the dependent list you can use the automatic variable SQLOBS in your test to break the recursion.
%if &sqlobs %then %do;
%dependencies(obj = &dependent_objectname.);
%end;
Also do NOT use a comma as the delimiter between the items listed in the OBJ parameter. The IN operator in SAS doesn't need them and they will cause trouble in the macro call.
select * from sashelp.class where name in ('Alfred' 'Alice') ;
So your macro could look like this:
%macro dependencies(object_list);
%local dependent_list ;
proc sql noprint;
select catq('1as',dependent_objectname)
into :dependent_list separated by ' '
from &_input.
where src_objectname in (&object_list)
and dependent_objectname is not null
;
quit;
%put Dependent Objects of (&object_list) = (&dependent_list);
%if &sqlobs %then %dependencies(&dependent_list);
%mend dependencies;
And here is a test case.
%let _input=sample;
data sample;
length src_objectname dependent_objectname $41 ;
input (_all_) (:) ;
cards;
object1 object2
object2 object3
object2 object4
;;;;
%dependencies('object1');
I write a macro sentence in SAS :
%macro loop;
%let sigmav=0.1;
.....
%let sigmav_new=std(V);
%if abs(%eval(&sigmav-&sigmav_new))<0.001 %then %do;
......
%mend;
But there are always errors of abs( ) and std( ). So I wonder whether there are special rules to express the function of abs() and std() in a macro. Hope for your help!
If you want to call a SAS function in a macro (and outside of a data step), you need to enclose it in %sysfunc().