Sorting and De-duping datasets in SAS

1. Proc Sort
   • By statement is used in Proc Sort to sort variables in a datset
   • By default, the specified variable(s) is sorted in ascending order
   • Descending option / keyword is used in the ‘By’ statement along with the variable to sort it in descending order
   • Only the variable followed by ‘descending’ will be sorted in descending order, the rest of them, if any will be sorted in ascending order
   • Noduprecs option – is used to extract only the non duplicate observations of the dataset
   • Nodupkey option – is used to extract only the non duplicate observations of a particular variable(s) specified in the By statement
2. Proc Print
   • By and Sum statement in SAS – using aggregate  functions in Proc Print procedure
3. Proc Append
   • To append SAS datasets, is to stack observations of one dataset over the other. It is like a horizontal join.
   • The datasets being appended must have the same variables (same data type and variable name)
   • Force option – to append datasets with uncommon variable names/attributes
   • Appending of datasets can be done using data and set statement, which is more of a union of datasets.