@@ -621,33 +621,33 @@ sub insert_at {

 sub insert_param_tag {

     my ($self, $param) = @_;

-    # Insert parameter tag

-    my @names;

-    my @placeholders;

-    

+    # Create insert parameter tag

     my $safety = $self->safety_character;

     my $q = $self->reserved_word_quote;

-    

+    my @columns;

+    my @placeholders;

     foreach my $column (keys %$param) {

         croak qq{"$column" is not safety column name}

           unless $column =~ /^[$safety\.]+$/;

-        

-        my $c = "$q$column$q";

-        $c =~ s/\./$q.$q/;

-        

-        push @names, $c;

-        push @placeholders, "{? $c}";

+        $column = "$q$column$q";

+        $column =~ s/\./$q.$q/;

+        push @columns, $column;

+        push @placeholders, "{? $column}";

     }

-    return '(' . join(', ', @names) . ') ' . 'values' .

-           ' (' . join(', ', @placeholders) . ')';

+    return '(' . join(', ', @columns) . ') ' . 'values ' .

+           '(' . join(', ', @placeholders) . ')'

 }

 sub include_model {

     my ($self, $name_space, $model_infos) = @_;

+    # Name space

     $name_space ||= '';

+    

+    # Get Model infomations

     unless ($model_infos) {

+

         # Load name space module

         croak qq{"$name_space" is invalid class name}

           if $name_space =~ /[^\w:]/;

@@ -664,13 +664,13 @@ sub include_model {

             push @$model_infos, $module

               if $module =~ s/\.pm$//;

         }

-        

         close $dh;

     }

+    # Include models

     foreach my $model_info (@$model_infos) {

-        # Model class, name, table

+        # Load model

         my $model_class;

         my $model_name;

         my $model_table;

@@ -684,8 +684,6 @@ sub include_model {

         }

         else { $model_class = $model_name = $model_table = $model_info }

         my $mclass = "${name_space}::$model_class";

-        

-        # Load

         croak qq{"$mclass" is invalid class name}

           if $mclass =~ /[^\w:]/;

         unless ($mclass->can('isa')) {

@@ -693,13 +691,11 @@ sub include_model {

             croak $@ if $@;

         }

-        # Instantiate

+        # Create model

         my $args = {};

         $args->{model_class} = $mclass if $mclass;

         $args->{name}        = $model_name if $model_name;

         $args->{table}       = $model_table if $model_table;

-        

-        # Create model

         $self->create_model($args);

     }

@@ -709,8 +705,8 @@ sub include_model {

 sub merge_param {

     my ($self, @params) = @_;

+    # Merge parameters

     my $param = {};

-    

     foreach my $p (@params) {

         foreach my $column (keys %$p) {

             if (exists $param->{$column}) {

@@ -730,7 +726,7 @@ sub merge_param {

 sub method {

     my $self = shift;

-    # Merge

+    # Register method

     my $methods = ref $_[0] eq 'HASH' ? $_[0] : {@_};

     $self->{_methods} = {%{$self->{_methods} || {}}, %$methods};

@@ -740,7 +736,7 @@ sub method {

 sub model {

     my ($self, $name, $model) = @_;

-    # Set

+    # Set model

     if ($model) {

         $self->models->{$name} = $model;

         return $self;

@@ -750,17 +746,17 @@ sub model {

     croak qq{Model "$name" is not included}

       unless $self->models->{$name};

-    # Get

+    # Get model

     return $self->models->{$name};

 }

 sub mycolumn {

     my ($self, $table, $columns) = @_;

+    # Create column clause

+    my @column;

     my $q = $self->reserved_word_quote;

-    

     $columns ||= [];

-    my @column;

     push @column, "$q$table$q.$q$_$q as $q$_$q" for @$columns;

     return join (', ', @column);

@@ -769,13 +765,14 @@ sub mycolumn {

 sub new {

     my $self = shift->SUPER::new(@_);

-    # Check attribute names

+    # Check attributes

     my @attrs = keys %$self;

     foreach my $attr (@attrs) {

-        croak qq{"$attr" is invalid attribute name}

+        croak qq{"$attr" is wrong name}

           unless $self->can($attr);

     }

-

+    

+    # Register tag

     $self->register_tag(

         '?'     => \&DBIx::Custom::Tag::placeholder,

         '='     => \&DBIx::Custom::Tag::equal,

@@ -796,13 +793,13 @@ sub new {

 sub not_exists { bless {}, 'DBIx::Custom::NotExists' }

 sub register_filter {

-    my $invocant = shift;

+    my $self = shift;

     # Register filter

     my $filters = ref $_[0] eq 'HASH' ? $_[0] : {@_};

-    $invocant->filters({%{$invocant->filters}, %$filters});

+    $self->filters({%{$self->filters}, %$filters});

-    return $invocant;

+    return $self;

 }

 sub register_tag { shift->query_builder->register_tag(@_) }

@@ -810,6 +807,7 @@ sub register_tag { shift->query_builder->register_tag(@_) }

 sub replace {

     my ($self, $join, $search, $replace) = @_;

+    # Replace

     my @replace_join;

     my $is_replaced;

     foreach my $j (@$join) {

@@ -832,15 +830,6 @@ our %SELECT_ARGS

 sub select {

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

-    # Reserved word quote

-    my $q = $self->reserved_word_quote;

-    

-    # Check argument names

-    foreach my $name (keys %args) {

-        croak qq{Argument "$name" is wrong name}

-          unless $SELECT_ARGS{$name};

-    }

-    

     # Arguments

     my $table = delete $args{table};

     my $tables = ref $table eq 'ARRAY' ? $table

@@ -854,11 +843,18 @@ sub select {

       unless ref $join eq 'ARRAY';

     my $relation = delete $args{relation};

     my $param = delete $args{param} || {};

+    my $query_return = $args{query};

+

+    # Check arguments

+    foreach my $name (keys %args) {

+        croak qq{Argument "$name" is wrong name}

+          unless $SELECT_ARGS{$name};

+    }

     # Add relation tables(DEPRECATED!);

     $self->_add_relation_table($tables, $relation);

-    # SQL stack

+    # Select statement

     my @sql;

     push @sql, 'select';

@@ -866,17 +862,16 @@ sub select {

     if ($columns) {

         $columns = [$columns] if ! ref $columns;

         foreach my $column (@$columns) {

-            unshift @$tables, @{$self->_tables($column)};

+            unshift @$tables, @{$self->_search_tables($column)};

             push @sql, ($column, ',');

         }

         pop @sql if $sql[-1] eq ',';

     }

-    

-    # "*" is default

     else { push @sql, '*' }

     # Table

     push @sql, 'from';

+    my $q = $self->reserved_word_quote;

     if ($relation) {

         my $found = {};

         foreach my $table (@$tables) {

@@ -889,34 +884,32 @@ sub select {

         push @sql, "$q$main_table$q";

     }

     pop @sql if ($sql[-1] || '') eq ',';

-    

-    # Main table

     croak "Not found table name" unless $tables->[-1];

-    # Add table names in param

-    unshift @$tables, @{$self->_tables(join(' ', keys %$param) || '')};

+    # Add tables in parameter

+    unshift @$tables, @{$self->_search_tables(join(' ', keys %$param) || '')};

     # Where

-    my $w = $self->_where_to_obj($where);

-    $param = keys %$param ? $self->merge_param($param, $w->param)

-                         : $w->param;

+    $where = $self->_where_to_obj($where);

+    $param = keys %$param ? $self->merge_param($param, $where->param)

+                          : $where->param;

     # String where

-    my $swhere = "$w";

+    my $where_clause = $where->to_string;

     # Add table names in where clause

-    unshift @$tables, @{$self->_tables($swhere)};

+    unshift @$tables, @{$self->_search_tables($where_clause)};

     # Push join

     $self->_push_join(\@sql, $join, $tables);

     # Add where clause

-    push @sql, $swhere;

+    push @sql, $where_clause;

     # Relation(DEPRECATED!);

-    $self->_push_relation(\@sql, $tables, $relation, $swhere eq '' ? 1 : 0);

+    $self->_push_relation(\@sql, $tables, $relation, $where_clause eq '' ? 1 : 0);

-    # Append statement

+    # Append

     push @sql, $append if $append;

     # SQL

@@ -924,12 +917,12 @@ sub select {

     # Create query

     my $query = $self->create_query($sql);

-    return $query if $args{query};

+    return $query if $query_return;

     # Execute query

     my $result = $self->execute(

         $query,

-        param  => $param, 

+        param => $param, 

         table => $tables,

         %args

     );

@@ -941,44 +934,35 @@ our %SELECT_AT_ARGS = (%SELECT_ARGS, where => 1, primary_key => 1);

 sub select_at {

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

+

+    # Arguments

+    my $primary_keys = delete $args{primary_key};

+    $primary_keys = [$primary_keys] unless ref $primary_keys;

+    my $where = delete $args{where};

+    my $param = delete $args{param};

-    # Check argument names

+    # Check arguments

     foreach my $name (keys %args) {

         croak qq{Argument "$name" is wrong name}

           unless $SELECT_AT_ARGS{$name};

     }

-    # Primary key

-    my $primary_keys = delete $args{primary_key};

-    $primary_keys = [$primary_keys] unless ref $primary_keys;

-    

     # Table

     croak qq{"table" option must be specified} unless $args{table};

     my $table = ref $args{table} ? $args{table}->[-1] : $args{table};

-    # Where clause

-    my $where = {};

-    if (exists $args{where}) {

-        my $where_columns = delete $args{where};

-        

+    # Where

+    my $where_param = {};

+    if ($where) {

         croak qq{"where" must be constant value or array reference}

-          unless !ref $where_columns || ref $where_columns eq 'ARRAY';

-        

-        $where_columns = [$where_columns] unless ref $where_columns;

-        

-        for(my $i = 0; $i < @$primary_keys; $i ++) {

-           $where->{$table . '.' . $primary_keys->[$i]} = $where_columns->[$i];

-        }

-    }

-    

-    if (exists $args{param}) {

-        my $param = delete $args{param};

+          unless !ref $where || ref $where eq 'ARRAY';

+        $where = [$where] unless ref $where;

         for(my $i = 0; $i < @$primary_keys; $i ++) {

-             delete $param->{$primary_keys->[$i]};

+           $where_param->{$table . '.' . $primary_keys->[$i]} = $where->[$i];

         }

     }

-    return $self->select(where => $where, %args);

+    return $self->select(where => $where_param, %args);

 }

 sub setup_model {

@@ -1319,7 +1303,7 @@ sub _remove_duplicate_table {

     return [keys %tables, $main_table ? $main_table : ()];

 }

-sub _tables {

+sub _search_tables {

     my ($self, $source) = @_;

     my $tables = [];

@@ -85,4 +85,4 @@ is($dbi->filters->{b}->(), 2);

 test 'invalid attribute name';

 eval {$dbi = DBIx::Custom->new(a => 1) };

-like ($@, qr/"a" is invalid attribute name/);

+like ($@, qr/name/);