choose updated table

[asuman]

suppose i have two tables, table A and table B both having same column and  data types.Either table A or B  can have updated values.

I have to fetch data from updated table only.What should be the query.

[PeterClemmensen]

What constitutes an 'updated value'? Please be more specific in your requirements and preferably illustrate your problem with sample data.

[asuman]

let updated value would be date.

[ballardw]

The following query examines properties of two data sets in the same library and reports the name of the data set with the latest modification datetime of for the tables:

proc sql;
   select memname
   from dictionary.tables
   where libname='SASHELP' and 
         memname in ('CLASS' 'BASEBALL')
   HAVING modate=max(modate)
   ;
quit;

It does not examine any values or the properties of any variables in either of the tables but is the closest I can think of to identify which table might be 'updated'.

[r_behata]

/*create sample data 1*/
data samp_a;
	set sashelp.class;
run;


/*Wait for 1 minute before processing the second sample data to simulate the scenario*/
Data _null_;
	wait=sleep(60,1);
Run;

/*create sample data 1*/
data samp_b;
	set sashelp.class;
run;



%let op=%sysfunc(open(samp_a));
*use the MODTE to obtain the modified date1 and time in sas datetime format;
%let mt1=%sysfunc(attrn(&op,MODTE));
%let op=%sysfunc(close(&op));


%let op=%sysfunc(open(samp_b));
*use the MODTE to obtain the modified date2 and time in sas datetime format;
%let mt2=%sysfunc(attrn(&op,MODTE));
%let op=%sysfunc(close(&op));


*Print the sas datetime values to log;
%put &=mt1 &=mt2;