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core/base/mp_guesspk.sas

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SAS

/**
@file
@brief Guess the primary key of a table
@details Tries to guess the primary key of a table based on the following
logic:
* Columns with nulls are ignored
* Return only column combinations that provide unique results
* Start from one column, then move out to composite keys of 2 to 6 columns
The library of the target should be assigned before using this macro.
Usage:
filename mc url
"https://raw.githubusercontent.com/sasjs/core/main/all.sas";
%inc mc;
%mp_guesspk(sashelp.class,outds=classpks)
@param [in] baseds The dataset to analyse
@param [out] outds= (mp_guesspk) Output dataset to contain the possible PKs
@param [in] max_guesses= (3) The total number of possible primary keys to
generate. A table may have multiple (unlikely) PKs, so no need to list them
all.
@param [in] min_rows= (5) The minimum number of rows a table should have in
order to try and guess the PK.
@param [in] ignore_cols (0) Space seperated list of columns which you are
sure are not part of the primary key (helps to avoid false positives)
@param [in] mdebug= Set to 1 to enable DEBUG messages and preserve outputs
<h4> SAS Macros </h4>
@li mf_getvarlist.sas
@li mf_getuniquename.sas
@li mf_wordsInstr1butnotstr2.sas
@li mf_nobs.sas
<h4> Related Macros </h4>
@li mp_getpk.sas
@version 9.3
@author Allan Bowe
**/
%macro mp_guesspk(baseds
,outds=mp_guesspk
,max_guesses=3
,min_rows=5
,ignore_cols=0
,mdebug=0
)/*/STORE SOURCE*/;
%local dbg;
%if &mdebug=1 %then %do;
%put &sysmacroname entry vars:;
%put _local_;
%end;
%else %let dbg=*;
/* declare local vars */
%local var vars vcnt i j k l tmpvar tmpds rows posspks ppkcnt;
%let vars=%upcase(%mf_getvarlist(&baseds));
%let vars=%mf_wordsInStr1ButNotStr2(str1=&vars,str2=%upcase(&ignore_cols));
%let vcnt=%sysfunc(countw(&vars));
%if &vcnt=0 %then %do;
%put &sysmacroname: &baseds has no variables! Exiting.;
%return;
%end;
/* get null count and row count */
%let tmpvar=%mf_getuniquename();
proc sql noprint;
create table _data_ as select
count(*) as &tmpvar
%do i=1 %to &vcnt;
%let var=%scan(&vars,&i);
,sum(case when &var is missing then 1 else 0 end) as &var
%end;
from &baseds;
/* transpose table and scan for not null cols */
proc transpose;
data _null_;
set &syslast end=last;
length vars $32767;
retain vars ;
if _name_="&tmpvar" then call symputx('rows',col1,'l');
else if col1=0 then vars=catx(' ',vars,_name_);
if last then call symputx('posspks',vars,'l');
run;
%let ppkcnt=%sysfunc(countw(&posspks));
%if &ppkcnt=0 %then %do;
%put &sysmacroname: &baseds has no non-missing variables! Exiting.;
%return;
%end;
proc sort data=&baseds(keep=&posspks) out=_data_ noduprec;
by _all_;
run;
%local pkds; %let pkds=&syslast;
%if &rows > %mf_nobs(&pkds) %then %do;
%put &sysmacroname: &baseds has no combination of unique records! Exiting.;
%return;
%end;
/* now check cardinality */
proc sql noprint;
create table _data_ as select
%do i=1 %to &ppkcnt;
%let var=%scan(&posspks,&i);
count(distinct &var) as &var
%if &i<&ppkcnt %then ,;
%end;
from &pkds;
/* transpose and sort by cardinality */
proc transpose;
proc sort; by descending col1;
run;
/* create initial PK list and re-order posspks list */
data &outds(keep=pkguesses);
length pkguesses $5000 vars $5000;
set &syslast end=last;
retain vars ;
vars=catx(' ',vars,_name_);
if col1=&rows then do;
pkguesses=_name_;
output;
end;
if last then call symputx('posspks',vars,'l');
run;
%if %mf_nobs(&outds) ge &max_guesses %then %do;
%put &sysmacroname: %mf_nobs(&outds) possible primary key values found;
%return;
%end;
%if &ppkcnt=1 %then %do;
%put &sysmacroname: No more PK guess possible;
%return;
%end;
/* begin scanning for uniques on pairs of PKs */
%let tmpds=%mf_getuniquename();
%local lev1 lev2;
%do i=1 %to &ppkcnt;
%let lev1=%scan(&posspks,&i);
%do j=2 %to &ppkcnt;
%let lev2=%scan(&posspks,&j);
%if &lev1 ne &lev2 %then %do;
/* check for two level uniqueness */
proc sort data=&pkds(keep=&lev1 &lev2) out=&tmpds noduprec;
by _all_;
run;
%if %mf_nobs(&tmpds)=&rows %then %do;
proc sql;
insert into &outds values("&lev1 &lev2");
%if %mf_nobs(&outds) ge &max_guesses %then %do;
%put &sysmacroname: Max PKs reached at Level 2 for &baseds;
%goto exit;
%end;
%end;
%end;
%end;
%end;
%if &ppkcnt=2 %then %do;
%put &sysmacroname: No more PK guess possible;
%goto exit;
%end;
/* begin scanning for uniques on PK triplets */
%local lev3;
%do i=1 %to &ppkcnt;
%let lev1=%scan(&posspks,&i);
%do j=2 %to &ppkcnt;
%let lev2=%scan(&posspks,&j);
%if &lev1 ne &lev2 %then %do k=3 %to &ppkcnt;
%let lev3=%scan(&posspks,&k);
%if &lev1 ne &lev3 and &lev2 ne &lev3 %then %do;
/* check for three level uniqueness */
proc sort data=&pkds(keep=&lev1 &lev2 &lev3) out=&tmpds noduprec;
by _all_;
run;
%if %mf_nobs(&tmpds)=&rows %then %do;
proc sql;
insert into &outds values("&lev1 &lev2 &lev3");
%if %mf_nobs(&outds) ge &max_guesses %then %do;
%put &sysmacroname: Max PKs reached at Level 3 for &baseds;
%goto exit;
%end;
%end;
%end;
%end;
%end;
%end;
%if &ppkcnt=3 %then %do;
%put &sysmacroname: No more PK guess possible;
%goto exit;
%end;
/* scan for uniques on up to 4 PK fields */
%local lev4;
%do i=1 %to &ppkcnt;
%let lev1=%scan(&posspks,&i);
%do j=2 %to &ppkcnt;
%let lev2=%scan(&posspks,&j);
%if &lev1 ne &lev2 %then %do k=3 %to &ppkcnt;
%let lev3=%scan(&posspks,&k);
%if &lev1 ne &lev3 and &lev2 ne &lev3 %then %do l=4 %to &ppkcnt;
%let lev4=%scan(&posspks,&l);
%if &lev1 ne &lev4 and &lev2 ne &lev4 and &lev3 ne &lev4 %then %do;
/* check for four level uniqueness */
proc sort data=&pkds(keep=&lev1 &lev2 &lev3 &lev4)
out=&tmpds noduprec;
by _all_;
run;
%if %mf_nobs(&tmpds)=&rows %then %do;
proc sql;
insert into &outds values("&lev1 &lev2 &lev3 &lev4");
%if %mf_nobs(&outds) ge &max_guesses %then %do;
%put &sysmacroname: Max PKs reached at Level 4 for &baseds;
%goto exit;
%end;
%end;
%end;
%end;
%end;
%end;
%end;
%if &ppkcnt=4 %then %do;
%put &sysmacroname: No more PK guess possible;
%goto exit;
%end;
/* scan for uniques on up to 4 PK fields */
%local lev5 m;
%do i=1 %to &ppkcnt;
%let lev1=%scan(&posspks,&i);
%do j=2 %to &ppkcnt;
%let lev2=%scan(&posspks,&j);
%if &lev1 ne &lev2 %then %do k=3 %to &ppkcnt;
%let lev3=%scan(&posspks,&k);
%if &lev1 ne &lev3 and &lev2 ne &lev3 %then %do l=4 %to &ppkcnt;
%let lev4=%scan(&posspks,&l);
%if &lev1 ne &lev4 and &lev2 ne &lev4 and &lev3 ne &lev4 %then
%do m=5 %to &ppkcnt;
%let lev5=%scan(&posspks,&m);
%if &lev1 ne &lev5 & &lev2 ne &lev5 & &lev3 ne &lev5 & &lev4 ne &lev5 %then %do;
/* check for four level uniqueness */
proc sort data=&pkds(keep=&lev1 &lev2 &lev3 &lev4 &lev5)
out=&tmpds noduprec;
by _all_;
run;
%if %mf_nobs(&tmpds)=&rows %then %do;
proc sql;
insert into &outds values("&lev1 &lev2 &lev3 &lev4 &lev5");
%if %mf_nobs(&outds) ge &max_guesses %then %do;
%put &sysmacroname: Max PKs reached at Level 5 for &baseds;
%goto exit;
%end;
%end;
%end;
%end;
%end;
%end;
%end;
%end;
%if &ppkcnt=5 %then %do;
%put &sysmacroname: No more PK guess possible;
%goto exit;
%end;
/* scan for uniques on up to 4 PK fields */
%local lev6 n;
%do i=1 %to &ppkcnt;
%let lev1=%scan(&posspks,&i);
%do j=2 %to &ppkcnt;
%let lev2=%scan(&posspks,&j);
%if &lev1 ne &lev2 %then %do k=3 %to &ppkcnt;
%let lev3=%scan(&posspks,&k);
%if &lev1 ne &lev3 and &lev2 ne &lev3 %then %do l=4 %to &ppkcnt;
%let lev4=%scan(&posspks,&l);
%if &lev1 ne &lev4 and &lev2 ne &lev4 and &lev3 ne &lev4 %then
%do m=5 %to &ppkcnt;
%let lev5=%scan(&posspks,&m);
%if &lev1 ne &lev5 & &lev2 ne &lev5 & &lev3 ne &lev5 & &lev4 ne &lev5
%then %do n=6 %to &ppkcnt;
%let lev6=%scan(&posspks,&n);
%if &lev1 ne &lev6 & &lev2 ne &lev6 & &lev3 ne &lev6
& &lev4 ne &lev6 & &lev5 ne &lev6 %then
%do;
/* check for four level uniqueness */
proc sort data=&pkds(keep=&lev1 &lev2 &lev3 &lev4 &lev5 &lev6)
out=&tmpds noduprec;
by _all_;
run;
%if %mf_nobs(&tmpds)=&rows %then %do;
proc sql;
insert into &outds
values("&lev1 &lev2 &lev3 &lev4 &lev5 &lev6");
%if %mf_nobs(&outds) ge &max_guesses %then %do;
%put &sysmacroname: Max PKs reached at Level 6 for &baseds;
%goto exit;
%end;
%end;
%end;
%end;
%end;
%end;
%end;
%end;
%end;
%if &ppkcnt=6 %then %do;
%put &sysmacroname: No more PK guess possible;
%goto exit;
%end;
%exit:
%if &mdebug=0 %then %do;
proc sql;
drop table &tmpds;
%end;
%mend mp_guesspk;