package DBIx::Custom;

our $VERSION = '0.1618';

use 5.008001;
use strict;
use warnings;

use base 'Object::Simple';

use Carp 'croak';
use DBI;
use DBIx::Custom::Result;
use DBIx::Custom::Query;
use DBIx::Custom::QueryBuilder;
use Encode qw/encode_utf8 decode_utf8/;

__PACKAGE__->attr([qw/data_source dbh default_bind_filter
                      default_fetch_filter password user/]);

__PACKAGE__->attr(cache => 1);
__PACKAGE__->attr(cache_method => sub {
    sub {
        my $self = shift;
        
        $self->{_cached} ||= {};
        
        if (@_ > 1) {
            $self->{_cached}{$_[0]} = $_[1] 
        }
        else {
            return $self->{_cached}{$_[0]}
        }
    }
});

__PACKAGE__->dual_attr('filters', default => sub { {} },
                                  inherit => 'hash_copy');
__PACKAGE__->attr(filter_check => 1);
__PACKAGE__->attr(query_builder  => sub {DBIx::Custom::QueryBuilder->new});
__PACKAGE__->attr(result_class => 'DBIx::Custom::Result');

# DBI methods
foreach my $method (qw/begin_work commit rollback/) {
    my $code = sub {
        my $self = shift;
        my $ret = eval {$self->dbh->$method};
        croak $@ if $@;
        return $ret;
    };
    no strict 'refs';
    my $pkg = __PACKAGE__;
    *{"${pkg}::$method"} = $code;
};

# Regster filter
__PACKAGE__->register_filter(
    encode_utf8 => sub { encode_utf8($_[0]) },
    decode_utf8 => sub { decode_utf8($_[0]) }
);

our $AUTOLOAD;

sub AUTOLOAD {
    my $self = shift;

    # Method
    my ($package, $method) = $AUTOLOAD =~ /^([\w\:]+)\:\:(\w+)$/;

    # Helper
    $self->{_helpers} ||= {};
    croak qq/Can't locate object method "$method" via "$package"/
      unless my $helper = $self->{_helpers}->{$method};

    # Run
    return $self->$helper(@_);
}

sub helper {
    my $self = shift;
    
    # Merge
    my $helpers = ref $_[0] eq 'HASH' ? $_[0] : {@_};
    $self->{_helpers} = {%{$self->{_helpers} || {}}, %$helpers};
    
    return $self;
}

sub connect {
    my $proto = shift;
    
    # Create
    my $self = ref $proto ? $proto : $proto->new(@_);
    
    # Information
    my $data_source = $self->data_source;
    my $user        = $self->user;
    my $password    = $self->password;
    
    
    # Connect
    my $dbh = eval {DBI->connect(
        $data_source,
        $user,
        $password,
        {
            RaiseError => 1,
            PrintError => 0,
            AutoCommit => 1,
        }
    )};
    
    # Connect error
    croak $@ if $@;
    
    # Database handle
    $self->dbh($dbh);
    
    return $self;
}

sub create_query {
    my ($self, $source) = @_;
    
    # Cache
    my $cache = $self->cache;
    
    # Create query
    my $query;
    if ($cache) {
        
        # Get query
        my $q = $self->cache_method->($self, $source);
        
        # Create query
        $query = DBIx::Custom::Query->new($q) if $q;
    }
    
    unless ($query) {

        # Create SQL object
        my $builder = $self->query_builder;
        
        # Create query
        $query = $builder->build_query($source);

        # Cache query
        $self->cache_method->($self, $source,
                             {sql     => $query->sql, 
                              columns => $query->columns})
          if $cache;
    }
    
    # Prepare statement handle
    my $sth;
    eval { $sth = $self->dbh->prepare($query->{sql})};
    $self->_croak($@, qq{. SQL: "$query->{sql}"}) if $@;
    
    # Set statement handle
    $query->sth($sth);
    
    return $query;
}

our %VALID_DELETE_ARGS
  = map { $_ => 1 } qw/table where append filter allow_delete_all/;

sub delete {
    my ($self, %args) = @_;
    
    # Check arguments
    foreach my $name (keys %args) {
        croak qq{"$name" is invalid argument}
          unless $VALID_DELETE_ARGS{$name};
    }
    
    # Arguments
    my $table            = $args{table} || '';
    my $where            = $args{where} || {};
    my $append = $args{append};
    my $filter           = $args{filter};
    my $allow_delete_all = $args{allow_delete_all};
    
    # Where keys
    my @where_keys = keys %$where;
    
    # Not exists where keys
    croak qq{"where" argument must be specified and } .
          qq{contains the pairs of column name and value}
      if !@where_keys && !$allow_delete_all;
    
    # Where clause
    my $where_clause = '';
    if (@where_keys) {
        $where_clause = 'where ';
        $where_clause .= "{= $_} and " for @where_keys;
        $where_clause =~ s/ and $//;
    }
    
    # Source of SQL
    my $source = "delete from $table $where_clause";
    $source .= " $append" if $append;
    
    # Execute query
    my $ret_val = $self->execute($source, param  => $where, 
                                 filter => $filter);
    
    return $ret_val;
}

sub delete_all { shift->delete(allow_delete_all => 1, @_) }

sub DESTROY { }

our %VALID_EXECUTE_ARGS = map { $_ => 1 } qw/param filter/;

sub execute{
    my ($self, $query, %args)  = @_;
    
    # Check arguments
    foreach my $name (keys %args) {
        croak qq{"$name" is invalid argument}
          unless $VALID_EXECUTE_ARGS{$name};
    }
    
    my $params = $args{param} || {};
    
    # First argument is the soruce of SQL
    $query = $self->create_query($query)
      unless ref $query;
    
    my $filter = $args{filter} || $query->filter || {};
    
    # Create bind value
    my $bind_values = $self->_build_bind_values($query, $params, $filter);
    
    # Execute
    my $sth      = $query->sth;
    my $affected;
    eval {$affected = $sth->execute(@$bind_values)};
    $self->_croak($@) if $@;
    
    # Return resultset if select statement is executed
    if ($sth->{NUM_OF_FIELDS}) {
        
        # Create result
        my $result = $self->result_class->new(
            sth            => $sth,
            default_filter => $self->default_fetch_filter,
            filters        => $self->filters,
            filter_check   => $self->filter_check
        );

        return $result;
    }
    return $affected;
}

our %VALID_INSERT_ARGS = map { $_ => 1 } qw/table param append filter/;

sub insert {
    my ($self, %args) = @_;

    # Check arguments
    foreach my $name (keys %args) {
        croak qq{"$name" is invalid argument}
          unless $VALID_INSERT_ARGS{$name};
    }
    
    # Arguments
    my $table  = $args{table} || '';
    my $param  = $args{param} || {};
    my $append = $args{append} || '';
    my $filter = $args{filter};
    
    # Insert keys
    my @insert_keys = keys %$param;
    
    # Templte for insert
    my $source = "insert into $table {insert_param "
               . join(' ', @insert_keys) . '}';
    $source .= " $append" if $append;
    
    # Execute query
    my $ret_val = $self->execute($source, param  => $param, 
                                          filter => $filter);
    
    return $ret_val;
}

sub register_filter {
    my $invocant = shift;
    
    # Register filter
    my $filters = ref $_[0] eq 'HASH' ? $_[0] : {@_};
    $invocant->filters({%{$invocant->filters}, %$filters});
    
    return $invocant;
}

our %VALID_SELECT_ARGS
  = map { $_ => 1 } qw/table column where append relation filter param/;

sub select {
    my ($self, %args) = @_;
    
    # Check arguments
    foreach my $name (keys %args) {
        croak qq{"$name" is invalid argument}
          unless $VALID_SELECT_ARGS{$name};
    }
    
    # Arguments
    my $tables = $args{table} || [];
    $tables = [$tables] unless ref $tables eq 'ARRAY';
    my $columns  = $args{column} || [];
    my $where    = $args{where};
    my $relation = $args{relation};
    my $append   = $args{append};
    my $filter   = $args{filter};
    
    # Source of SQL
    my $source = 'select ';
    
    # Column clause
    if (@$columns) {
        foreach my $column (@$columns) {
            $source .= "$column, ";
        }
        $source =~ s/, $/ /;
    }
    else {
        $source .= '* ';
    }
    
    # Table
    $source .= 'from ';
    foreach my $table (@$tables) {
        $source .= "$table, ";
    }
    $source =~ s/, $/ /;
    
    # Where clause
    my $param;
    if (ref $where eq 'HASH') {
        $param = $where;
        $source .= 'where (';
        foreach my $where_key (keys %$where) {
            $source .= "{= $where_key} and ";
        }
        $source =~ s/ and $//;
        $source .= ') ';
    }
    elsif (ref $where eq 'ARRAY') {
        my$where_str = $where->[0] || '';
        $param = $where->[1];
        
        $source .= "where ($where_str) ";
    }
    
    # Relation
    if ($relation) {
        $source .= $where ? "and " : "where ";
        foreach my $rkey (keys %$relation) {
            $source .= "$rkey = " . $relation->{$rkey} . " and ";
        }
    }
    $source =~ s/ and $//;
    
    # Append some statement
    $source .= " $append" if $append;
    
    # Execute query
    my $result = $self->execute($source, param  => $param, 
                                         filter => $filter);
    
    return $result;
}

our %VALID_UPDATE_ARGS
  = map { $_ => 1 } qw/table param where append filter allow_update_all/;

sub update {
    my ($self, %args) = @_;
    
    # Check arguments
    foreach my $name (keys %args) {
        croak qq{"$name" is invalid argument}
          unless $VALID_UPDATE_ARGS{$name};
    }
    
    # Arguments
    my $table            = $args{table} || '';
    my $param            = $args{param} || {};
    my $where            = $args{where} || {};
    my $append = $args{append} || '';
    my $filter           = $args{filter};
    my $allow_update_all = $args{allow_update_all};
    
    # Update keys
    my @update_keys = keys %$param;
    
    # Where keys
    my @where_keys = keys %$where;
    
    # Not exists where keys
    croak qq{"where" argument must be specified and } .
          qq{contains the pairs of column name and value}
      if !@where_keys && !$allow_update_all;
    
    # Update clause
    my $update_clause = '{update_param ' . join(' ', @update_keys) . '}';
    
    # Where clause
    my $where_clause = '';
    my $new_where = {};
    
    if (@where_keys) {
        $where_clause = 'where ';
        $where_clause .= "{= $_} and " for @where_keys;
        $where_clause =~ s/ and $//;
    }
    
    # Source of SQL
    my $source = "update $table $update_clause $where_clause";
    $source .= " $append" if $append;
    
    # Rearrange parameters
    foreach my $wkey (@where_keys) {
        
        if (exists $param->{$wkey}) {
            $param->{$wkey} = [$param->{$wkey}]
              unless ref $param->{$wkey} eq 'ARRAY';
            
            push @{$param->{$wkey}}, $where->{$wkey};
        }
        else {
            $param->{$wkey} = $where->{$wkey};
        }
    }
    
    # Execute query
    my $ret_val = $self->execute($source, param  => $param, 
                                 filter => $filter);
    
    return $ret_val;
}

sub update_all { shift->update(allow_update_all => 1, @_) };

sub _build_bind_values {
    my ($self, $query, $params, $filter) = @_;
    
    # binding values
    my @bind_values;

    # Filter
    $filter ||= {};
    
    # Parameter
    $params ||= {};
    
    # Check filter
    $self->_check_filter($self->filters, $filter,
                         $self->default_bind_filter, $params)
      if $self->filter_check;
    
    # Build bind values
    my $count = {};
    foreach my $column (@{$query->columns}) {
        
        # Value
        my $value = ref $params->{$column} eq 'ARRAY'
                  ? $params->{$column}->[$count->{$column} || 0]
                  : $params->{$column};
        
        # Filtering
        my $fname = $filter->{$column} || $self->default_bind_filter || '';
        my $filter_func = $fname ? $self->filters->{$fname} : undef;
        push @bind_values, $filter_func
                         ? $filter_func->($value)
                         : $value;
        
        # Count up 
        $count->{$column}++;
    }
    
    return \@bind_values;
}

sub _check_filter {
    my ($self, $filters, $filter, $default_filter, $params) = @_;
    
    # Filter name not exists
    foreach my $fname (values %$filter) {
        croak qq{Bind filter "$fname" is not registered}
          unless exists $filters->{$fname};
    }
    
    # Default filter name not exists
    croak qq{Default bind filter "$default_filter" is not registered}
      if $default_filter && ! exists $filters->{$default_filter};
    
    # Column name not exists
    foreach my $column (keys %$filter) {
        
        croak qq{Column name "$column" in bind filter is not found in paramters}
          unless exists $params->{$column};
    }
}

sub _croak {
    my ($self, $error, $append) = @_;
    $append ||= "";
    
    # Verbose
    if ($Carp::Verbose) { croak $error }
    
    # Not verbose
    else {
        
        # Remove line and module infromation
        my $at_pos = rindex($error, ' at ');
        $error = substr($error, 0, $at_pos);
        $error =~ s/\s+$//;
        
        croak "$error$append";
    }
}

1;

=head1 NAME

DBIx::Custom - DBI interface, having hash parameter binding and filtering system

=head1 SYNOPSYS

Connect to the database.
    
    use DBIx::Custom;
    my $dbi = DBIx::Custom->connect(data_source => "dbi:mysql:database=dbname",
                                    user => 'ken', password => '!LFKD%$&');

Insert, update, and delete

    # Insert 
    $dbi->insert(table  => 'books',
                 param  => {title => 'Perl', author => 'Ken'},
                 filter => {title => 'encode_utf8'});
    
    # Update 
    $dbi->update(table  => 'books', 
                 param  => {title => 'Perl', author => 'Ken'}, 
                 where  => {id => 5},
                 filter => {title => 'encode_utf8'});
    
    # Update all
    $dbi->update_all(table  => 'books',
                     param  => {title => 'Perl'},
                     filter => {title => 'encode_utf8'});
    
    # Delete
    $dbi->delete(table  => 'books',
                 where  => {author => 'Ken'},
                 filter => {title => 'encode_utf8'});
    
    # Delete all
    $dbi->delete_all(table => 'books');

Select

    # Select
    my $result = $dbi->select(table => 'books');
    
    # Select, more complex
    my $result = $dbi->select(
        table  => 'books',
        column => [qw/author title/],
        where  => {author => 'Ken'},
        append => 'order by id limit 5',
        filter => {title => 'encode_utf8'}
    );
    
    # Select, join table
    my $result = $dbi->select(
        table    => ['books', 'rental'],
        column   => ['books.name as book_name']
        relation => {'books.id' => 'rental.book_id'}
    );
    
    # Select, more flexible where
    my $result = $dbi->select(
        table  => 'books',
        where  => ['{= author} and {like title}', 
                   {author => 'Ken', title => '%Perl%'}]
    );

Execute SQL

    # Execute SQL
    $dbi->execute("select title from books");
    
    # Execute SQL with hash binding and filtering
    $dbi->execute("select id from books where {= author} and {like title}",
                  param  => {author => 'ken', title => '%Perl%'},
                  filter => {title => 'encode_utf8'});

    # Create query and execute it
    my $query = $dbi->create_query(
        "select id from books where {= author} and {like title}"
    );
    $dbi->execute($query, param => {author => 'Ken', title => '%Perl%'})

Other features.

    # Default filter
    $dbi->default_bind_filter('encode_utf8');
    $dbi->default_fetch_filter('decode_utf8');

    # Get DBI object
    my $dbh = $dbi->dbh;

Fetch row.

    # Fetch
    while (my $row = $result->fetch) {
        # ...
    }
    
    # Fetch hash
    while (my $row = $result->fetch_hash) {
        
    }
    
=head1 DESCRIPTIONS

L<DBIx::Custom> is one of L<DBI> interface modules,
such as L<DBIx::Class>, L<DBIx::Simple>.

This module is not O/R mapper. O/R mapper is useful,
but you must learn many syntax of the O/R mapper,
which is almost another language.
Created SQL statement is offten not effcient and damage SQL performance.
so you have to execute raw SQL in the end.

L<DBIx::Custom> is middle area between L<DBI> and O/R mapper.
L<DBIx::Custom> provide flexible hash parameter binding and filtering system,
and suger methods, such as C<select()>, C<update()>, C<delete()>, C<select()>
to execute SQL easily.

L<DBIx::Custom> respects SQL. SQL is very complex and not beautiful,
but de-facto standard,
so all people learing database know it.
If you already know SQL,
you learn a little thing to use L<DBIx::Custom>.

See L<DBIx::Custom::Guides> for more details.

=head1 ATTRIBUTES

=head2 C<cache>

    my $cache = $dbi->cache;
    $dbi      = $dbi->cache(1);

Enable parsed L<DBIx::Custom::Query> object caching.
Default to 1.

=head2 C<cache_method>

    $dbi          = $dbi->cache_method(\&cache_method);
    $cache_method = $dbi->cache_method

Method to set and get caches.

B<Example:>

    $dbi->cache_method(
        sub {
            my $self = shift;
            
            $self->{_cached} ||= {};
            
            if (@_ > 1) {
                $self->{_cached}{$_[0]} = $_[1] 
            }
            else {
                return $self->{_cached}{$_[0]}
            }
        }
    );

=head2 C<data_source>

    my $data_source = $dbi->data_source;
    $dbi            = $dbi->data_source("DBI:mysql:database=dbname");

Data source.
C<connect()> method use this value to connect the database.

=head2 C<dbh>

    my $dbh = $dbi->dbh;
    $dbi    = $dbi->dbh($dbh);

L<DBI> object. You can call all methods of L<DBI>.

=head2 C<default_bind_filter>

    my $default_bind_filter = $dbi->default_bind_filter
    $dbi                    = $dbi->default_bind_filter('encode_utf8');

Default filter when parameter binding is executed.

=head2 C<default_fetch_filter>

    my $default_fetch_filter = $dbi->default_fetch_filter;
    $dbi                     = $dbi->default_fetch_filter('decode_utf8');

Default filter when row is fetched.

=head2 C<filters>

    my $filters = $dbi->filters;
    $dbi        = $dbi->filters(\%filters);

Filter functions.
"encode_utf8" and "decode_utf8" is registered by default.

=head2 C<filter_check>

    my $filter_check = $dbi->filter_check;
    $dbi             = $dbi->filter_check(0);

Enable filter check. 
Default to 1.
This check maybe damege performance.
If you require performance, set C<filter_check> attribute to 0.

=head2 C<password>

    my $password = $dbi->password;
    $dbi         = $dbi->password('lkj&le`@s');

Password.
C<connect()> method use this value to connect the database.

=head2 C<query_builder>

    my $sql_class = $dbi->query_builder;
    $dbi          = $dbi->query_builder(DBIx::Custom::QueryBuilder->new);

SQL builder. C<query_builder()> must be 
the instance of L<DBIx::Custom::QueryBuilder> subclass.
Default to L<DBIx::Custom::QueryBuilder> object.

=head2 C<result_class>

    my $result_class = $dbi->result_class;
    $dbi             = $dbi->result_class('DBIx::Custom::Result');

Result class for select statement.
Default to L<DBIx::Custom::Result>.

=head2 C<user>

    my $user = $dbi->user;
    $dbi     = $dbi->user('Ken');

User name.
C<connect()> method use this value to connect the database.
    
=head1 METHODS

L<DBIx::Custom> inherits all methods from L<Object::Simple>
and implements the following new ones.

=head2 begin_work

    $dbi->begin_work;

Start transaction.
This is same as L<DBI>'s C<begin_work>.

L<DBIx::Custom> inherits all methods from L<Object::Simple>
and implements the following new ones.

=head2 commit

    $dbi->commit;

Commit transaction.
This is same as L<DBI>'s C<commit>.

=head2 C<connect>

    my $dbi = DBIx::Custom->connect(data_source => "dbi:mysql:database=dbname",
                                    user => 'ken', password => '!LFKD%$&');

Create a new L<DBIx::Custom> object and connect to the database.
L<DBIx::Custom> is a wrapper of L<DBI>.
C<AutoCommit> and C<RaiseError> options are true, 
and C<PrintError> option is false by default. 

=head2 C<create_query>
    
    my $query = $dbi->create_query(
        "select * from books where {= author} and {like title};"
    );

Create the instance of L<DBIx::Custom::Query> from the source of SQL.
If you want to get high performance,
use C<create_query()> method and execute it by C<execute()> method
instead of suger methods.

    $dbi->execute($query, {author => 'Ken', title => '%Perl%'});

=head2 C<execute>

    my $result = $dbi->execute($query,  param => $params, filter => \%filter);
    my $result = $dbi->execute($source, param => $params, filter => \%filter);

Execute query or the source of SQL.
Query is L<DBIx::Custom::Query> object.
Return value is L<DBIx::Custom::Result> if select statement is executed,
or the count of affected rows if insert, update, delete statement is executed.

B<Example:>

    my $result = $dbi->execute(
        "select * from books where {= author} and {like title}", 
        param => {author => 'Ken', title => '%Perl%'}
    );
    
    while (my $row = $result->fetch) {
        my $author = $row->[0];
        my $title  = $row->[1];
    }

=head2 C<delete>

    $dbi->delete(table  => $table,
                 where  => \%where,
                 append => $append,
                 filter => \%filter);

Execute delete statement.
C<delete> method have C<table>, C<where>, C<append>, and C<filter> arguments.
C<table> is a table name.
C<where> is where clause. this must be hash reference.
C<append> is a string added at the end of the SQL statement.
C<filter> is filters when parameter binding is executed.
Return value of C<delete()> is the count of affected rows.

B<Example:>

    $dbi->delete(table  => 'books',
                 where  => {id => 5},
                 append => 'some statement',
                 filter => {id => 'encode_utf8'});

=head2 C<delete_all>

    $dbi->delete_all(table => $table);

Execute delete statement to delete all rows.
Arguments is same as C<delete> method,
except that C<delete_all> don't have C<where> argument.
Return value of C<delete_all()> is the count of affected rows.

B<Example:>
    
    $dbi->delete_all(table => 'books');

=head2 C<(experimental) helper>

    $dbi->helper(
        update_or_insert => sub {
            my $self = shift;
            # do something
        },
        find_or_create   => sub {
            my $self = shift;
            # do something
        }
    );

Register helper methods. These method is called from L<DBIx::Custom> object directory.

    $dbi->update_or_insert;
    $dbi->find_or_create;

=head2 C<insert>

    $dbi->insert(table  => $table, 
                 param  => \%param,
                 append => $append,
                 filter => \%filter);

Execute insert statement.
C<insert> method have C<table>, C<param>, C<append>
and C<filter> arguments.
C<table> is a table name.
C<param> is the pairs of column name value. this must be hash reference.
C<append> is a string added at the end of the SQL statement.
C<filter> is filters when parameter binding is executed.
This is overwrites C<default_bind_filter>.
Return value of C<insert()> is the count of affected rows.

B<Example:>

    $dbi->insert(table  => 'books', 
                 param  => {title => 'Perl', author => 'Taro'},
                 append => "some statement",
                 filter => {title => 'encode_utf8'})

=head2 C<register_filter>

    $dbi->register_filter(%filters);
    $dbi->register_filter(\%filters);
    
Register filter. Registered filters is available in the following attributes
or arguments.

=over 4

=item *

C<default_bind_filter>, C<default_fetch_filter>

=item *

C<filter> argument of C<insert()>, C<update()>,
C<update_all()>, C<delete()>, C<delete_all()>, C<select()>
methods

=item *

C<execute()> method

=item *

C<default_filter> and C<filter> of C<DBIx::Custom::Query>

=item *

C<default_filter> and C<filter> of C<DBIx::Custom::Result>

=back

B<Example:>

    $dbi->register_filter(
        encode_utf8 => sub {
            my $value = shift;
            
            require Encode;
            
            return Encode::encode('UTF-8', $value);
        },
        decode_utf8 => sub {
            my $value = shift;
            
            require Encode;
            
            return Encode::decode('UTF-8', $value)
        }
    );

=head2 rollback

    $dbi->rollback;

Rollback transaction.
This is same as L<DBI>'s C<rollback>.

=head2 C<select>
    
    my $result = $dbi->select(table    => $table,
                              column   => [@column],
                              where    => \%where,
                              append   => $append,
                              relation => \%relation,
                              filter   => \%filter);

Execute select statement.
C<select> method have C<table>, C<column>, C<where>, C<append>,
C<relation> and C<filter> arguments.
C<table> is a table name.
C<where> is where clause. this is normally hash reference.
C<append> is a string added at the end of the SQL statement.
C<filter> is filters when parameter binding is executed.

B<Example:>

    # select * from books;
    my $result = $dbi->select(table => 'books');
    
    # select * from books where title = ?;
    my $result = $dbi->select(table => 'books', where => {title => 'Perl'});
    
    # select title, author from books where id = ? for update;
    my $result = $dbi->select(
        table  => 'books',
        column => ['title', 'author'],
        where  => {id => 1},
        appned => 'for update'
    );
    
    # select books.name as book_name from books, rental
    # where books.id = rental.book_id;
    my $result = $dbi->select(
        table    => ['books', 'rental'],
        column   => ['books.name as book_name']
        relation => {'books.id' => 'rental.book_id'}
    );

If you use more complex condition,
you can specify a array reference to C<where> argument.

    my $result = $dbi->select(
        table  => 'books',
        column => ['title', 'author'],
        where  => ['{= title} or {like author}',
                   {title => '%Perl%', author => 'Ken'}]
    );

First element is a string. it contains tags,
such as "{= title} or {like author}".
Second element is paramters.

=head2 C<update>

    $dbi->update(table  => $table, 
                 param  => \%params,
                 where  => \%where,
                 append => $append,
                 filter => \%filter)

Execute update statement.
C<update> method have C<table>, C<param>, C<where>, C<append>
and C<filter> arguments.
C<table> is a table name.
C<param> is column-value pairs. this must be hash reference.
C<where> is where clause. this must be hash reference.
C<append> is a string added at the end of the SQL statement.
C<filter> is filters when parameter binding is executed.
This is overwrites C<default_bind_filter>.
Return value of C<update()> is the count of affected rows.

B<Example:>

    $dbi->update(table  => 'books',
                 param  => {title => 'Perl', author => 'Taro'},
                 where  => {id => 5},
                 append => "some statement",
                 filter => {title => 'encode_utf8'});

=head2 C<update_all>

    $dbi->update_all(table  => $table, 
                     param  => \%params,
                     filter => \%filter,
                     append => $append);

Execute update statement to update all rows.
Arguments is same as C<update> method,
except that C<update_all> don't have C<where> argument.
Return value of C<update_all()> is the count of affected rows.

B<Example:>

    $dbi->update_all(table  => 'books', 
                     param  => {author => 'taro'},
                     filter => {author => 'encode_utf8'});

=head1 STABILITY

L<DBIx::Custom> is now stable. APIs keep backword compatible in the feature.

=head1 BUGS

Please tell me bugs if found.

C<< <kimoto.yuki at gmail.com> >>

L<http://github.com/yuki-kimoto/DBIx-Custom>

=head1 AUTHOR

Yuki Kimoto, C<< <kimoto.yuki at gmail.com> >>

=head1 COPYRIGHT & LICENSE

Copyright 2009 Yuki Kimoto, all rights reserved.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

=cut