SQL Approaches

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Learning how to use a new language is an arduous task for users. A new system which uses a familiar language is usually adopted smoothly by the users. This approach views the Web as a huge database, where each record matches a web page, and designs an SQL-like language to support effective and flexible searches.

Syntax (SQL + Regular Expressions)

view source print? 1 query := SELECT select_cause 2            FROM from_clause 3            [ WHERE condition_clause ]; 4 select_clause := arguments 5 from_clause := path

• Find documents about Toronto that reside in servers in Canada.
  
  

  view source print? 1 SELECT d.url, d.title 2   FROM Document d SUCH THAT d MENTIONS "Toronto" 3   WHERE d.url CONTAINS ".ca$";



• Find documents about “excursions” near WWW6 homepage.
  
  

  view source print? 1 SELECT d.url, d.title 2   FROM Document d SUCH THAT d MENTIONS 3     "www6conf.slac.stanford.edu" (→|→→|→→→) d 4   WHERE d.text CONTAINS "excursions";

  
  

  Path Regular Expression
  →	Local link: same server
  ⇒	Global link: different server
  →|⇒	Path of length one, either local or global
  →*	Local path of any length



• Find educational pages containing the keyword “database.”
  
  

  view source print? 1 SELECT url 2   FROM http://*.edu/* 3   WHERE keyword LIKE 'database';

  
  where the symbol ‘*’ is a wild card matching any string.