Difference between 'retain' and 'keep' statement in SAS

The 'retain' statement in SAS is used to save the value of a variable from the previous iteration of the data step, while the 'keep' statement is used to specify which variables to keep in the output dataset.

Using the 'retain' statement can be helpful when you want to carry forward the value of a variable from one iteration to the next, without needing to reassign it. On the other hand, the 'keep' statement is used to subset the variables that you want to include in the output dataset, discarding the rest.

It's important to note that the 'retain' statement affects the data step execution and the order in which variables are processed, while the 'keep' statement only affects the final output.

Both statements are useful in different contexts and understanding their differences can help SAS programmers optimize their code efficiently.