[英]How to write conditional where statement in SAS Proc SQL?
我有一个可用于多种条件的宏。
%macro Average(data=, tablename=, element=, variablename=, time =);
PROC SQL;
CREATE TABLE &tablename. AS
SELECT ID, AVG(&element.) AS &variablename.
FROM &data.
WHERE date_time < &time or date_time > &time + 1 /*first where condition*/
GROUP BY ID;
QUIT;
%mend;
/*second where condition*/ WHERE &Lower. < date_time < &Upper.
/*third where condition*/ WHERE &BP > 0 and &SP<100
我想将所有这三个where语句放到sql宏中,而不是复制宏三遍。 但是我怎么能意识到呢?
如果要有选择地调用where
条件的不同组合,则可以执行以下操作,将它们设置为默认值为1
除非将它们分配给其他where
条件:
%macro Average(data=, tablename=, element=, variablename=, time=
,whr1=1
,whr2=1
,whr3=1);
PROC SQL;
CREATE TABLE &tablename. AS
SELECT ID, AVG(&element.) AS &variablename.
FROM &data.
WHERE (&whr1) and (&whr2) and (&whr3)
GROUP BY ID;
QUIT;
%mend;
然后,您可以使用where
条件调用该宏,例如:
%Average(whr1=%str(date_time < &time or date_time > &time + 1))
%Average(whr1=%str(date_time < &time or date_time > &time + 1)
,whr2=%str(&Lower. < date_time < &Upper.)
,whr3=%str(WHERE &BP > 0 and &SP<100))
只需使用%if%then%else宏条件,并在此处定义一个新参数whr:
%macro Average(data=, tablename=, element=, variablename=, time =, whr=);
PROC SQL;
CREATE TABLE &tablename. AS
SELECT ID, AVG(&element.) AS &variablename.
FROM &data.
%if &whr=1 %then %do;
WHERE date_time < &time or date_time > &time + 1 /*first where condition*/
%end;
%else %if &whr=2 %then %do;
WHERE &Lower. < date_time < &Upper.
%end;
%else %if &whr=3 %then %do;
WHERE &BP > 0 and &SP<100
%end;
%else %put 'NO WHERE SPECIFIED';
GROUP BY ID;
QUIT;
%mend;
如果您指定参数声明whr = 1,它将是默认值。 使用%if%then%else,您还可以在宏内部使用不同的条件,这意味着如果您想使用第一个where语句(如果某些条件为真),则可以指定它们。
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