CTX_THES Package, 14 of 26

NT

This function returns all narrower terms of a phrase as recorded in the specified thesaurus.

Syntax 1: Table Result

CTX_THES.NT(restab IN OUT NOCOPY EXP_TAB,
             phrase IN VARCHAR2, 
             lvl    IN NUMBER DEFAULT 1,
             tname  IN VARCHAR2 DEFAULT 'DEFAULT');

Syntax 2: String Result

CTX_THES.NT(phrase IN VARCHAR2, 
             lvl    IN NUMBER DEFAULT 1,
             tname  IN VARCHAR2 DEFAULT 'DEFAULT') 
RETURN VARCHAR2;

restab

Optionally, specify the name of the expansion table to store the results. This table must be of type EXP_TAB which the system defines as follows:

type exp_rec is record (
    xrel varchar2(12),
    xlevel number,
    xphrase varchar2(256)
);
type exp_tab is table of exp_rec index by binary_integer;

See Also:
For more information about EXP_TAB, see "CTX_THES Result Tables and Data Types" in Appendix B, "Result Tables".

phrase

Specify phrase to lookup in thesaurus.

lvl

Specify how many levels of narrower terms to return. For example 2 means get the narrower terms of the narrower terms of the phrase.

tname

Specify thesaurus name. If not specified, system default thesaurus is used.

Returns

This function returns a string of narrower terms in the form:

 {nt1}|{nt2}|{nt3} ...

Example

String Result

Consider a thesaurus named MY_THES that has an entry for cat as follows:

cat
 NT domestic cat
 NT wild cat
 BT mammal
mammal
 BT animal
domestic cat
 NT Persian cat
 NT Siamese cat

To look up the narrower terms for cat down to two levels, issue the following statements:

declare 
  terms varchar2(2000); 
begin 
  terms := ctx_thes.nt('CAT', 2, 'MY_THES'); 
  dbms_output.put_line('the narrower expansion for CAT is: '||terms); 
end;

This code produces the following output:

the narrower expansion for CAT is: {cat}|{domestic cat}|{wild cat}|{Persian 
cat}|{Siamese cat}

Table Result

The following code does an narrower term lookup for canine using the table result:

declare
  xtab ctx_thes.exp_tab;
begin
  ctx_thes.nt(xtab, 'canine', 2, 'my_thesaurus');
  for i in 1..xtab.count loop
    dbms_output.put_line(lpad(' ', 2*xtab(i).xlevel) || 
    xtab(i).xrel || ' ' || xtab(i).xphrase);
  end loop;
end;