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## This patch is from rails 4.2-stable. Remove it when 4.2.6 is released
## https://github.com/rails/rails/issues/21108
module ActiveRecord
module ConnectionAdapters
class AbstractMysqlAdapter < AbstractAdapter
# SHOW VARIABLES LIKE 'name'
def show_variable(name)
variables = select_all("select @@#{name} as 'Value'", 'SCHEMA')
variables.first['Value'] unless variables.empty?
rescue ActiveRecord::StatementInvalid
nil
end
# MySQL is too stupid to create a temporary table for use subquery, so we have
# to give it some prompting in the form of a subsubquery. Ugh!
def subquery_for(key, select)
subsubselect = select.clone
subsubselect.projections = [key]
subselect = Arel::SelectManager.new(select.engine)
subselect.project Arel.sql(key.name)
# Materialized subquery by adding distinct
# to work with MySQL 5.7.6 which sets optimizer_switch='derived_merge=on'
subselect.from subsubselect.distinct.as('__active_record_temp')
end
end
end
end
module ActiveRecord
module ConnectionAdapters
class MysqlAdapter < AbstractMysqlAdapter
ADAPTER_NAME = 'MySQL'.freeze
# Get the client encoding for this database
def client_encoding
return @client_encoding if @client_encoding
result = exec_query(
"select @@character_set_client",
'SCHEMA')
@client_encoding = ENCODINGS[result.rows.last.last]
end
end
end
end
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