* SELECT 基本 [#g8767459]

** where句を設定する [#u5289657]
*** 比較 [#x9a2add7]
 $rs->search({ age => 20 })                        # WHERE age = 20                   =
 $rs->search({ age => {'!=', 20} })                # WHERE age != 20                  !=
 $rs->search({ age => {'>' => 20} })               # WHERE age > 20                   >
 $rs->search({ age => undef })                     # WHERE age is NULL                NULL
*** 論理演算子 [#bc1f7be7]
 $rs->search([{ age => 20 },{ age => 30 }])        # WHERE age = 20 OR age = 30       OR
 $rs->search({ age => 20, name => 'taro })         # WHERE age = 20 AND name = 'taro' AND
 $rs->search({ age => { '>' => 10, '<' => 20 }})   # WHERE age > 10 AND age < 20      AND  同じカラムを使う場合
 $rs->search({ age => [10, 20] })                  # WHERE age BETWEEN 10 AND 20      BETWEEN
 $rs->search_like({ name => '%taro%' })            # WHERE name LIKE '%taro%'         LIKE
 $rs->search({ id => {-in => \@ids}})              # WHERE id in (1,2,3..)            IN


http://search.cpan.org/perldoc?DBIx::Class::ResultSet#search

** 検索を実行する [#p7adce4a]
 my $rs = $schema->resultset('User')->search({ age => 20});

*** プライマリキーで検索する [#he6a13f8]
 my $user = $schema->resultset('User')->find(5);
見つからないときはundefが返ってくる。

** 検索結果を取り出す [#m298a625]
*** 順次取り出す [#f11c67d6]
 while (my $user = $rs->next) { print $user->name; }
*** 1行だけ取り出す [#c2654ac7]
 my $user = $schema->resultset('User')->single({ age => 20});
*** 最初の行を取り出す [#s12d6f89]
 my $user = $schema->resultset('User')->search({ age => 20})->first;
*** 全行取り出す [#kb43997d]
 my @users = $schema->resultset('User')->search({ age => 20})->all;

** ORDER BY [#h7a857b5]
 $rs->search({},{ 
  order_by => [ 'name', { -desc => 'id' } ] # ORDER BY name ASC, id DESC
  });                                       # 'name' は { -asc => 'name' } の省略形                     
http://search.cpan.org/perldoc?SQL::Abstract#ORDER_BY_CLAUSES

*** NULLを0と見なしてORDER BYする方法 [#ec445214]
(多分)DBICではCASE式が使えないので、COALESCE関数を使う。例えばpointカラムを降順でソートするには以下のようにする。
 $rs->search(undef, {
  order_by => [ { '-desc' => \'COALESCE(point, 0)' } ],
 });

** GROUP BY [#g35ffed7]
 $rs->search({},{
     select   => ['name', {SUM => 'point'}],
     as       => ['name', 'point'],
     group_by => ['name'],
 });
 $point = $rs->next->get_column('point');

** LIMIT / OFFSET [#y76174dc]
 $rs->search({},{ order_by => 'id' })->slice(0,20); # slice($offset,$limit)

** 特定のカラムのみSELECT(AS演算子)[#hf28370c]
 $rs->search({},{
    select => [ 'name', 'age' ],
    as     => [ 'name', '年齢'],
 });
 print $r->name, $r->get_column('年齢');

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