mirror of
https://github.com/rails/rails.git
synced 2022-11-09 12:12:34 -05:00
69 lines
1.9 KiB
Ruby
69 lines
1.9 KiB
Ruby
module Arel
|
|
module Visitors
|
|
class Oracle < Arel::Visitors::ToSql
|
|
private
|
|
|
|
def visit_Arel_Nodes_SelectStatement o
|
|
o = order_hacks(o)
|
|
|
|
# if need to select first records without ORDER BY and GROUP BY and without DISTINCT
|
|
# then can use simple ROWNUM in WHERE clause
|
|
if o.limit && o.orders.empty? && !o.offset && o.cores.first.projections.first !~ /^DISTINCT /
|
|
o.cores.last.wheres.push Nodes::LessThanOrEqual.new(
|
|
Nodes::SqlLiteral.new('ROWNUM'), o.limit
|
|
)
|
|
o.limit = nil
|
|
return super
|
|
end
|
|
|
|
if o.limit && o.offset
|
|
o = o.dup
|
|
limit = o.limit.to_i
|
|
offset = o.offset
|
|
o.limit = nil
|
|
o.offset = nil
|
|
sql = super(o)
|
|
return <<-eosql
|
|
SELECT * FROM (
|
|
SELECT raw_sql_.*, rownum raw_rnum_
|
|
FROM (#{sql}) raw_sql_
|
|
WHERE rownum <= #{offset.value.to_i + limit}
|
|
)
|
|
WHERE #{visit offset}
|
|
eosql
|
|
end
|
|
|
|
if o.limit
|
|
o = o.dup
|
|
limit = o.limit
|
|
o.limit = nil
|
|
return "SELECT * FROM (#{super(o)}) WHERE ROWNUM <= #{limit}"
|
|
end
|
|
|
|
super
|
|
end
|
|
|
|
def visit_Arel_Nodes_Offset o
|
|
"raw_rnum_ > #{visit o.value}"
|
|
end
|
|
|
|
###
|
|
# Hacks for the order clauses specific to Oracle
|
|
def order_hacks o
|
|
return o if o.orders.empty?
|
|
return o unless o.cores.any? do |core|
|
|
core.projections.any? do |projection|
|
|
/DISTINCT.*FIRST_VALUE/ === projection
|
|
end
|
|
end
|
|
orders = o.orders.map { |x| visit x }.join(', ').split(',')
|
|
o.orders = []
|
|
orders.each_with_index do |order, i|
|
|
o.orders <<
|
|
Nodes::SqlLiteral.new("alias_#{i}__#{' DESC' if /\bdesc$/i === order}")
|
|
end
|
|
o
|
|
end
|
|
end
|
|
end
|
|
end
|