Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "If any of the checks fail, you should do ROLLBACK instead of COMMIT."

A block of code is set as follows:

CREATE TABLE accounts(owner text, balance numeric, amount numeric);
INSERT INTO accounts VALUES ('Bob',100);
INSERT INTO accounts VALUES ('Mary',200);

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

CREATE OR REPLACE FUNCTION fibonacci_seq(num integer)
 RETURNS SETOF integer AS $$
DECLARE
  a int := 0;
  b int := 1;
BEGIN
  IF (num <= 0)
    THEN RETURN;
  END IF;

  RETURN NEXT a;
  LOOP
    EXIT WHEN num <= 1;
    RETURN NEXT b;

      num = num - 1;
      SELECT b, a + b INTO a, b;
  END LOOP;
END;
$$ LANGUAGE plpgsql;

Any command-line input or output is written as follows:

$ psql -c "SELECT 1 AS test"

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Enter some values into the columns, as seen in the preceding screenshot, and click on the Debug button."