NAME

       SQL::Statement::Function - abstract base class for all function executing terms

SYNOPSIS

         # this class does not have a common constructor, because all derived classes
         # have their special requirements

DESCRIPTION

       SQL::Statement::Function is an abstract base class providing the interface for all function executing
       terms.

INHERITANCE

         SQL::Statement::Function
         ISA SQL::Statement::Term

METHODS

   DESTROY
       Destroys the term and undefines the weak reference to the owner as well as the reference to the parameter
       list.

NAME

       SQL::Statement::Function::UserFunc - implements executing a perl subroutine

SYNOPSIS

         # create an user function term with an SQL::Statement object as owner,
         # specifying the function name, the subroutine name (full qualified)
         # and the parameters to the subroutine
         my $term = SQL::Statement::Function::UserFunc->new( $owner, $name, $sub, \@params );
         # access the result of that operation
         $term->value( $eval );

DESCRIPTION

       SQL::Statement::Function::UserFunc implements a term which returns the result of the specified
       subroutine.

INHERITANCE

         SQL::Statement::Function
         ISA SQL::Statement::Term

METHODS

   new
       Instantiates a new "SQL::Statement::Function::UserFunc" instance.

   value
       Invokes the given subroutine with the values of the params and return it's result:

           my @params = map { $_->value($eval); } @{ $self->{PARAMS} };
           return $subpkg->$subname( $self->{OWNER}, @params );

NAME

       SQL::Statement::Function::NumericEval - implements numeric evaluation of a term

SYNOPSIS

         # create an user function term with an SQL::Statement object as owner,
         # specifying the expression to evaluate and the parameters to the subroutine
         my $term = SQL::Statement::NumericEval->new( $owner, $expr, \@params );
         # access the result of that operation
         $term->value( $eval );

DESCRIPTION

       SQL::Statement::Function::NumericEval implements the numeric evaluation of a term. All parameters are
       expected to be numeric.

INHERITANCE

         SQL::Statement::Function::NumericEval
         ISA SQL::Statement::Function
           ISA SQL::Statement::Term

METHODS

   new
       Instantiates a new "SQL::Statement::Function::NumericEval" instance.  Takes $owner, $expr and \@params as
       arguments (in specified order).

   value
       Returns the result of the evaluated expression.

NAME

       SQL::Statement::Function::Trim - implements the built-in trim function support

SYNOPSIS

         # create an trim function term with an SQL::Statement object as owner,
         # specifying the spec, char and the parameters to the subroutine
         my $term = SQL::Statement::Trim->new( $owner, $spec, $char, \@params );
         # access the result of that operation
         $term->value( $eval );

DESCRIPTION

       SQL::Statement::Function::Trim implements string trimming.

INHERITANCE

         SQL::Statement::Function::Trim
         ISA SQL::Statement::Function
           ISA SQL::Statement::Term

METHODS

   new
       Instantiates a new "SQL::Statement::Function::Trim" instance.  Takes $owner, $spec, $char and \@params as
       arguments (in specified order).

       Meaning of the parameters:

       $spec
           Can  be  on of 'LEADING', 'TRAILING' 'BOTH'. Trims the leading chars, trailing chars or at both ends,
           respectively.

           Defaults to 'BOTH'.

       $char
           The character to trim - defaults to ' '

       \@params
           Expected to be an array with exact 1 element (more are not evaluated).

   value
       Returns the trimmed value of first parameter argument.

NAME

       SQL::Statement::Function::SubString - implements the built-in sub-string function support

SYNOPSIS

         # create an substr function term with an SQL::Statement object as owner,
         # specifying the start and length of the sub string to extract from the
         # first element of \@params
         my $term = SQL::Statement::SubString->new( $owner, $start, $length, \@params );
         # access the result of that operation
         $term->value( $eval );

DESCRIPTION

       SQL::Statement::Function::SubString implements a sub-string extraction term.

INHERITANCE

         SQL::Statement::Function::SubString
         ISA SQL::Statement::Function
           ISA SQL::Statement::Term

METHODS

   new
       Instantiates a new "SQL::Statement::Function::SubString" instance.  Takes  $owner,  $start,  $length  and
       \@params as arguments (in specified order).

       Meaning of the parameters:

       $start
           Specifies the start position to extract the sub-string. This is expected to be a SQL::Statement::Term
           instance. The first character in a string has the position 1.

       $length
           Specifies  the  length  of  the  extracted  sub-string. This is expected to be a SQL::Statement::Term
           instance.

           If omitted, everything to the end of the string is returned.

       \@params
           Expected to be an array with exact 1 element (more are not evaluated).

   value
       Returns the extracted sub-string value from first parameter argument.

NAME

       SQL::Statement::Function::StrConcat - implements the built-in string concatenation

SYNOPSIS

         # create an substr function term with an SQL::Statement object as owner
         # and \@params to concatenate
         my $term = SQL::Statement::StrConcat->new( $owner, \@params );
         # access the result of that operation
         $term->value( $eval );

DESCRIPTION

       SQL::Statement::Function::StrConcat implements a string concatenation term.

INHERITANCE

         SQL::Statement::Function::StrConcat
         ISA SQL::Statement::Function
           ISA SQL::Statement::Term

METHODS

   new
       Instantiates a new "SQL::Statement::Function::StrConcat" instance.

   value
       Returns the concatenated string composed of the parameter values.

AUTHOR AND COPYRIGHT

       Copyright (c) 2009-2020 by Jens Rehsack: rehsackATcpan.org

       All rights reserved.

       You may distribute this module under the terms of either the GNU General Public License or  the  Artistic
       License, as specified in the Perl README file.

perl v5.30.3                                       2020-10-23                      SQL::Statement::Function(3pm)