Text::Query::BuildSQL - Base class for SQL query builders
package Text::Query::BuildSQLsqldb;
use Text::Query::BuildSQL;
use vars qw(@ISA);
@ISA = qw(Text::Query::BuildSQL);
Defines all the build_* functions to build a syntax tree. The tree nodes
are [ operator scope operand operand... ]. The build_final_expression function
translate the syntax tree in a where clause using the resolve method.
If the scope of the search is not specified (simple query or advanced query without
scope operator), the scope is set to the list of comma separated fields provided
by the -fields_searched option.
The resulting where clause is placed in the select order provided with
the -select option, if any.
The string enclosed in single quotes must match exactly. The <string> token stands for an arbitrary string. A description enclosed in [something ...] means repeated 0 or N times.
expr: 'or' scope expr [expr ...]
'and' scope expr [expr ...]
'not' scope expr
'near' scope expr_literal expr_literal
'forbiden' scope expr_literal [expr_literal ...]
'mandatory' scope expr_literal [expr_literal ...]
'optional' scope expr_literal [expr_literal ...]
'literal' scope <string>
expr_literal: literal scope <string>
scope: <string>
where clause string corresponding to the Q1 syntax tree.
mandatory and forbiden syntactic nodes to their boolean
equivalents. If it has_relevance returns false and
there is at least one mandatory word, the first mandatory word
is added to the list of optional words.
Returns true if relevance ranking is possible, false if not. It
is used by the sortplusminus function. Returns false by default.
If relevance ranking is not possible, the semantic of the simple
search is slighthly modified. When asking for +a b c it shows
all the documents containing a and (b or c).
The normal behaviour is to return all the documents containing a
and to sort them to show first those containing (b or c). When
relevance ranking is not available the b, c search terms are
therefore useless. That is why we decided to change the semantic
of the query if no relevance ranking is available.
If provided the string returned by build_final_expression substitutes the
__WHERE__ tag with the where string generated by the resolve function.
The substituted string is the return value of the build_final_expression.
If not set the return value of the build_final_expression is the result
of the resolve function.
FIELDS_LIST is a list of comma separated field names. It is used as the
default scope if no scope is provided in the query string. The build_final_expression
function will croak if this option is not provided and no scope operator
were used.
Text::Query(3) Text::Query::Build(3)
Loic Dachary (loic@senga.org)