LIS618 lecture 5
Thomas Krichel
2003-02-26
structure
• operations on any file (database)
– connectors
– booleans
– set handling
– display
• file-specifics
– bluesheet
– Introduction to structured queries
Use of connectors
• Connectors are used to put several words
together.
• One instance where this is useful is when
you have words that on their own mean
different things.
• For example "mate" is a herbal beverage
consumed in South America. Looking for
mate on the Internet retrieves a lot of
singles' pages.
example: terms related to "mate"
What other terms to be used?
– matear
– matero
– cebar
– cebador
– yerba
– bombilla
(drink mate)
(mate drinker)
(prepare mate)
(mate preparer)
(mate herb)
(mate straw)
connectors
I
• '(W)' requires terms to appear one after
the other next to each other e.g.
'yerba(W)mate?' matches "yerba mate".
• '(i W)' where i is an integer, means
followed by at most i words, e.g.
'ceba?(3W)mate?' matches "cebar un
maravilloso mate" but not "cebador guapo
mirando un buen mate"
connectors
II
• '(N)' requires terms to be next to each
other e.g. 'yerba(N)mate?' matches "yerba
mate" or "mate yerba".
• '(i N)' where i is an integer, means
proximity by at most i words, e.g.
'ceba?(3N)mate?' matches "cebar mate"
or "matear con la cebadora".
• '(S)' searches for the occurrence of
connected terms in the same paragraph.
using Boolean operators
• In your query, you can combine several
expressions with Boolean operators
• Example: "S LIBRARY(W)SCHOOL? AND
DISTANCE(W)EDUCATION"
• But I usually do not issue such fancy
queries.
executing several searches
• there can be several searches done
sequentially, and the results sets are
saved by the system.
• Each time the system assigns a set
number, Si,
• These can be combined in Boolean
expressions, e.g. 's S1 or S2 and S3'
• Remember that Boolean operations are
set-theoretic!
Boolean operators on sets
• when using Booleans, be aware that "and"
has higher precedence than "or".
• Thus:
a or b and c
is not the same as
(a or b) and c
but it is
a or (b and c)
• use parenthesis when in doubt
DS (display sets)
• This command can be executed any time
to review the sets that have been formed
since the last B (begin) command.
• This can be useful to review your search
history.
the target command
• "target set" where set is a search result
set creates a subset of the "statistically
most relevant results" in the original set.
• I have not seen details about how this
subset is computed.
• new result set is being formed.
display: the type command
type set/format/range
• set is a result set
• format is a format
• range can be
– start – end
• start is a record number to start
• end is a record number to end
– all
standard delivery formats
•
•
•
•
•
2 -- full record except abstract
3 or medium – citation
5 or long – full except full text
6 or free – title and dialog number
8 or short – title plus indexing terms
– useful to find other indexing terms
• 9 or full – everything
• KWIC or K – keywords in context
options for delivery
• I once tried to email results to me, to no
avail
• You can save the html of the search
results in the browser.
• You can print the results within the
browser.
Looking at database structure
• Up until now, we have looked at
commands that take a full-text view of the
database.
• Such commands can be executed for
every database.
• If we want to make more precise queries,
we have to take account of database
structure.
blue sheet
• each database name is linked to a blueish
pop-up window called the blue sheet for
the database
• This is called the bluesheet.
• It contains the details of the database.
closer look at the bluesheet
• file description
• subject coverage (free vocabulary)
• format options, lists all formats
– by number (internal)
– by dialog web format (external, i.e. crossdatabase)
• search options
– basic index, i.e. subject contents
– additional index, i.e. non-subject
basic vs additional index
• the basic index
– has information that is relevant to the
substantive contents of the data
– usually is indexed by word, i.e. connectors are
required
• the additional index
– has data that is not relevant to the substantive
matter
– usually indexed by phrase, i.e. connectors are
not required
search options: basic index
• select without qualifiers searches in all
fields in the basic index
• bluesheet lists field indicators available for
a database
• also note if field is indexed by word or
phrase. proximity searching only works
with word indices. when phrases are
indexed you don't need proximity
indicators
http://openlib.org/home/krichel
Thank you for your attention!