Conditionals

There are two main conditional constructs: IF ... END IF and CASE ... END CASE, which are similar to the Java switch construct or the Perl given construct. Both constructs evaluate a Boolean condition and execute the branch only if the condition results in a true value. Both IF and CASE allow for multiple branches with different condition evaluations—ELSIF and WHEN respectively—and both allow for a catch-all branch named ELSE.

Listing 13 shows how to use an IF statement. First, we extract the maximum file size from the files table and check it against the predefined file sizes to print out a human readable file size with the measurement unit:

testdb=> DO $code$
   DECLARE
     file_name text;
     file_size numeric;
     size_kb int := 1024;
     size_mb numeric := size_kb * size_kb;
     size_gb numeric := size_mb * size_mb;
     unit text;
   BEGIN
    ...