PROC SQL: Why Use It When Simple IF/THEN Statements Work?

Efficiency is an important concern for computer programs that undertake large tasks, especially when the programs are used many times. We compare two methods for updating values in a large database. The first method uses standard SAS "datastepping" with IF statements. The second method takes advantage of some of the power available in the SAS SQL Procedure. A comparison of the two methods on real data sets encountered in operations on a large national household survey, with more than 16,000 records and over 3,000 fields, shows that striking improvement is achieved using the more sophisticated SQL tools.