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99 lines
3.1 KiB
Ruby
99 lines
3.1 KiB
Ruby
# frozen_string_literal: true
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module Arel # :nodoc: all
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module Visitors
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class MySQL < Arel::Visitors::ToSql
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private
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def visit_Arel_Nodes_Bin(o, collector)
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collector << "BINARY "
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visit o.expr, collector
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end
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def visit_Arel_Nodes_UnqualifiedColumn(o, collector)
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visit o.expr, collector
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end
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###
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# :'(
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# To retrieve all rows from a certain offset up to the end of the result set,
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# you can use some large number for the second parameter.
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# https://dev.mysql.com/doc/refman/en/select.html
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def visit_Arel_Nodes_SelectStatement(o, collector)
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if o.offset && !o.limit
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o.limit = Arel::Nodes::Limit.new(18446744073709551615)
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end
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super
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end
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def visit_Arel_Nodes_SelectCore(o, collector)
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o.froms ||= Arel.sql("DUAL")
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super
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end
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def visit_Arel_Nodes_Concat(o, collector)
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collector << " CONCAT("
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visit o.left, collector
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collector << ", "
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visit o.right, collector
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collector << ") "
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collector
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end
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def visit_Arel_Nodes_IsNotDistinctFrom(o, collector)
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collector = visit o.left, collector
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collector << " <=> "
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visit o.right, collector
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end
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def visit_Arel_Nodes_IsDistinctFrom(o, collector)
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collector << "NOT "
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visit_Arel_Nodes_IsNotDistinctFrom o, collector
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end
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def visit_Arel_Nodes_Regexp(o, collector)
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infix_value o, collector, " REGEXP "
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end
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def visit_Arel_Nodes_NotRegexp(o, collector)
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infix_value o, collector, " NOT REGEXP "
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end
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# no-op
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def visit_Arel_Nodes_NullsFirst(o, collector)
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visit o.expr, collector
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end
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# In the simple case, MySQL allows us to place JOINs directly into the UPDATE
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# query. However, this does not allow for LIMIT, OFFSET and ORDER. To support
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# these, we must use a subquery.
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def prepare_update_statement(o)
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if o.offset || has_group_by_and_having?(o) ||
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has_join_sources?(o) && has_limit_or_offset_or_orders?(o)
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super
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else
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o
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end
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end
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alias :prepare_delete_statement :prepare_update_statement
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# MySQL doesn't automatically create a temporary table for use subquery, so we have
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# to give it some prompting in the form of a subsubquery.
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def build_subselect(key, o)
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subselect = super
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# Materialize subquery by adding distinct
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# to work with MySQL 5.7.6 which sets optimizer_switch='derived_merge=on'
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unless has_limit_or_offset_or_orders?(subselect)
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core = subselect.cores.last
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core.set_quantifier = Arel::Nodes::Distinct.new
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end
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Nodes::SelectStatement.new.tap do |stmt|
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core = stmt.cores.last
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core.froms = Nodes::Grouping.new(subselect).as("__active_record_temp")
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core.projections = [Arel.sql(quote_column_name(key.name))]
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end
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end
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end
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end
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end
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