1
0
Fork 0
mirror of https://github.com/rails/rails.git synced 2022-11-09 12:12:34 -05:00
rails--rails/activerecord/lib/arel/visitors/mysql.rb
Ryuta Kamizono 859fba7c4b Handle DELETE with LIMIT in Arel
MySQL supports DELETE with LIMIT and ORDER BY.

https://dev.mysql.com/doc/refman/8.0/en/delete.html

Before:

```
  Post Destroy (1.0ms)  DELETE FROM `posts` WHERE `posts`.`id` IN (SELECT `id` FROM (SELECT `posts`.`id` FROM `posts` WHERE `posts`.`author_id` = ? ORDER BY `posts`.`id` ASC LIMIT ?) __active_record_temp)  [["author_id", 1], ["LIMIT", 1]]
```

After:

```
  Post Destroy (0.4ms)  DELETE FROM `posts` WHERE `posts`.`author_id` = ? ORDER BY `posts`.`id` ASC LIMIT ?  [["author_id", 1], ["LIMIT", 1]]
```
2018-09-30 21:21:54 +09:00

95 lines
2.5 KiB
Ruby

# frozen_string_literal: true
module Arel # :nodoc: all
module Visitors
class MySQL < Arel::Visitors::ToSql
private
def visit_Arel_Nodes_Union(o, collector, suppress_parens = false)
unless suppress_parens
collector << "( "
end
collector = case o.left
when Arel::Nodes::Union
visit_Arel_Nodes_Union o.left, collector, true
else
visit o.left, collector
end
collector << " UNION "
collector = case o.right
when Arel::Nodes::Union
visit_Arel_Nodes_Union o.right, collector, true
else
visit o.right, collector
end
if suppress_parens
collector
else
collector << " )"
end
end
def visit_Arel_Nodes_Bin(o, collector)
collector << "BINARY "
visit o.expr, collector
end
def visit_Arel_Nodes_UnqualifiedColumn(o, collector)
visit o.expr, collector
end
###
# :'(
# http://dev.mysql.com/doc/refman/5.0/en/select.html#id3482214
def visit_Arel_Nodes_SelectStatement(o, collector)
if o.offset && !o.limit
o.limit = Arel::Nodes::Limit.new(18446744073709551615)
end
super
end
def visit_Arel_Nodes_SelectCore(o, collector)
o.froms ||= Arel.sql("DUAL")
super
end
def visit_Arel_Nodes_UpdateStatement(o, collector)
collector << "UPDATE "
collector = visit o.relation, collector
unless o.values.empty?
collector << " SET "
collector = inject_join o.values, collector, ", "
end
collect_where_for(o, collector)
end
def visit_Arel_Nodes_Concat(o, collector)
collector << " CONCAT("
visit o.left, collector
collector << ", "
visit o.right, collector
collector << ") "
collector
end
def collect_where_for(o, collector)
unless o.wheres.empty?
collector << " WHERE "
collector = inject_join o.wheres, collector, " AND "
end
unless o.orders.empty?
collector << " ORDER BY "
collector = inject_join o.orders, collector, ", "
end
maybe_visit o.limit, collector
end
end
end
end