- BASE SAS INTERVIEW QUESTIONS ON DATA STEP AND PROC STEP HOW TO
- BASE SAS INTERVIEW QUESTIONS ON DATA STEP AND PROC STEP CODE
With the DATA step, you are giving the program instructions on how you want the data to be processed.
BASE SAS INTERVIEW QUESTIONS ON DATA STEP AND PROC STEP CODE
However, each process has a big difference in the philosophy of how you code it. Each process needs to know what data is coming in, the calculations needed to be done, and which records to output. How do you strategize when coding each process?Īs the programmer, you are the coach with how both of these processes handle the data. Once the final table is created in memory, it is then sent to the output table described in the CREATE TABLE statement. Temporary tables are also created in memory where the code can then place data as it is calculating and building the results. Once it has come up with a plan, then any tables in the FROM statement are loaded into the data engine where they can then be accessed in memory.
BASE SAS INTERVIEW QUESTIONS ON DATA STEP AND PROC STEP HOW TO
The optimizer then intelligently strategizes how to execute the code. When a proc SQL statement is executed, the first step is the SQL optimizer scans the query inside the statement. If the DATA step is a sequential process by the record, then it is best to think of the SQL procedure as a simultaneous process for all the records. Once the buffer is filled, then the records are then populated to the output SAS data set described in the DATA statement. From here the records are then loaded sequentially into the output buffer. Once the buffer is loaded, records start to get processed in the program data vector (PDV) which is a temporary placement for the record so that any calculations can be computed. It starts out by taking records from the data source in the SET statement and loading them into the input buffer. The DATA step is a sequential process, it brings in, calculates, and outputs a single record at a time. How does SAS process data?īoth methods are ways to do to create and manipulate data, but how after decades is one not much more accepted than the other? Let’s take a look at how each one takes in and processes data: DATA Step This new enhancement to the language allowed traditional SAS programmers to continue using the DATA step while also letting programmers with a database background to easily pick up the SAS language. With the early releases of SAS 6 in the 1990s, SAS introduced the SQL procedure into the base language so that the SQL language was available as well as the DATA step for their programming. Throughout the 1980s, SQL became so popular among all relational databases that the American National Standards Institute (ANSI) developed standards so that it would remain consistent across all platforms. Meanwhile in the 1970s relational databases started taking off and the SQL language was developed by researchers at IBM as a way to program within a database. The first formal release of SAS was in 1972, which included the DATA step and a few other original procedures but not the SQL procedure. History – How these processes got started in SAS