• Add the URL to the inverted list if its contents include the keyword.


• If the keyword does not exist in the inverted list, add it and the URL to the list if the URL contents include the keyword.


• List the index of the keyword. If the keyword is empty, list all indexes.

   SQL> CREATE TABLE  keywords (
     2    kwID     INT AUTO_INCREMENT PRIMARY KEY,
     3    keyword  VARCHAR(64) );

   SQL> CREATE TABLE  url_title (
     2    urlID  INT AUTO_INCREMENT PRIMARY KEY,
     3    url    VARCHAR(128),
     4    title  VARCHAR(128) );
  
   SQL> CREATE TABLE  www_index (
     2    kwID   INT,
     3    urlID  INT,
     4    PRIMARY KEY ( kwID, urlID ),
     5    FOREIGN KEY ( kwID  ) REFERENCES  keywords  ( kwID ),
     6    FOREIGN KEY ( urlID ) REFERENCES  url_title ( urlID ) );