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author | Carlos Antonio da Silva <carlosantoniodasilva@gmail.com> | 2012-06-22 09:30:00 -0300 |
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committer | Carlos Antonio da Silva <carlosantoniodasilva@gmail.com> | 2012-06-22 09:32:41 -0300 |
commit | e5cd300becab8e05f4568a402e3fce4f4497733a (patch) | |
tree | 238a37bc01acbcebd7a463fc08ba8e813a4d79c5 /guides/source | |
parent | 6aae17e85613fe8c2816ba278f9348f168692479 (diff) | |
download | rails-e5cd300becab8e05f4568a402e3fce4f4497733a.tar.gz rails-e5cd300becab8e05f4568a402e3fce4f4497733a.tar.bz2 rails-e5cd300becab8e05f4568a402e3fce4f4497733a.zip |
Add changelog entry and guide updates for pluck with multiple columns
Diffstat (limited to 'guides/source')
-rw-r--r-- | guides/source/active_record_querying.textile | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/guides/source/active_record_querying.textile b/guides/source/active_record_querying.textile index 4b14671efc..101988c59e 100644 --- a/guides/source/active_record_querying.textile +++ b/guides/source/active_record_querying.textile @@ -609,8 +609,8 @@ And this will give you a single +Order+ object for each date where there are ord The SQL that would be executed would be something like this: <sql> -SELECT date(created_at) as ordered_date, sum(price) as total_price -FROM orders +SELECT date(created_at) as ordered_date, sum(price) as total_price +FROM orders GROUP BY date(created_at) </sql> @@ -627,9 +627,9 @@ Order.select("date(created_at) as ordered_date, sum(price) as total_price").grou The SQL that would be executed would be something like this: <sql> -SELECT date(created_at) as ordered_date, sum(price) as total_price -FROM orders -GROUP BY date(created_at) +SELECT date(created_at) as ordered_date, sum(price) as total_price +FROM orders +GROUP BY date(created_at) HAVING sum(price) > 100 </sql> @@ -1286,26 +1286,36 @@ Client.connection.select_all("SELECT * FROM clients WHERE id = '1'") h3. +pluck+ -<tt>pluck</tt> can be used to query a single column from the underlying table of a model. It accepts a column name as argument and returns an array of values of the specified column with the corresponding data type. +<tt>pluck</tt> can be used to query a single or multiple columns from the underlying table of a model. It accepts a list of column names as argument and returns an array of values of the specified columns with the corresponding data type. <ruby> Client.where(:active => true).pluck(:id) # SELECT id FROM clients WHERE active = 1 +# => [1, 2, 3] Client.uniq.pluck(:role) # SELECT DISTINCT role FROM clients +# => ['admin', 'member', 'guest'] + +Client.pluck(:id, :name) +# SELECT clients.id, clients.name FROM clients +# => [[1, 'David'], [2, 'Jeremy'], [3, 'Jose']] </ruby> +pluck+ makes it possible to replace code like <ruby> Client.select(:id).map { |c| c.id } +# or +Client.select(:id).map { |c| [c.id, c.name] } </ruby> with <ruby> Client.pluck(:id) +# or +Client.pluck(:id, :name) </ruby> h3. +ids+ |