From 753010ac39f5442c92ec0bdd7484f0fd72ad8ac0 Mon Sep 17 00:00:00 2001 From: Rick Olson Date: Sun, 19 Mar 2006 17:42:51 +0000 Subject: add support for COUNT(DISTINCT id) queries in sqlite2 (closes #4300) [Rick Olson] git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3979 5ecf4fe2-1ee6-0310-87b1-e25e094e27de --- .../connection_adapters/sqlite_adapter.rb | 23 ++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) (limited to 'activerecord/lib/active_record/connection_adapters') diff --git a/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb index 579bc471d2..bc874ee58b 100644 --- a/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb +++ b/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb @@ -36,7 +36,7 @@ module ActiveRecord # "Downgrade" deprecated sqlite API if SQLite.const_defined?(:Version) - ConnectionAdapters::SQLiteAdapter.new(db, logger) + ConnectionAdapters::SQLite2Adapter.new(db, logger) else ConnectionAdapters::DeprecatedSQLiteAdapter.new(db, logger) end @@ -331,8 +331,27 @@ module ActiveRecord end end end + + class SQLite2Adapter < SQLiteAdapter # :nodoc: + # SQLite 2 does not support COUNT(DISTINCT) queries: + # + # select COUNT(DISTINCT ArtistID) from CDs; + # + # In order to get the number of artists we execute the following statement + # + # SELECT COUNT(ArtistID) FROM (SELECT DISTINCT ArtistID FROM CDs); + def execute(sql, name = nil) #:nodoc: + if sql =~ /count\(distinct ([^\)]+)\)( AS \w+)? (.*)/i + distinct_column = $1 + distinct_query = $3 + column_name = distinct_column.split('.').last + sql = "SELECT COUNT(#{column_name}) FROM (SELECT DISTINCT #{distinct_column} #{distinct_query})" + end + log(sql, name) { @connection.execute(sql) } + end + end - class DeprecatedSQLiteAdapter < SQLiteAdapter # :nodoc: + class DeprecatedSQLiteAdapter < SQLite2Adapter # :nodoc: def insert(sql, name = nil, pk = nil, id_value = nil) execute(sql, name = nil) id_value || @connection.last_insert_rowid -- cgit v1.2.3