diff options
Diffstat (limited to 'lib/arel/visitors/mssql.rb')
-rw-r--r-- | lib/arel/visitors/mssql.rb | 62 |
1 files changed, 40 insertions, 22 deletions
diff --git a/lib/arel/visitors/mssql.rb b/lib/arel/visitors/mssql.rb index 23dc06a936..0e5b75ec59 100644 --- a/lib/arel/visitors/mssql.rb +++ b/lib/arel/visitors/mssql.rb @@ -1,6 +1,8 @@ module Arel module Visitors class MSSQL < Arel::Visitors::ToSql + RowNumber = Struct.new :children + private # `top` wouldn't really work here. I.e. User.select("distinct first_name").limit(10) would generate @@ -10,30 +12,43 @@ module Arel "" end - def visit_Arel_Nodes_SelectStatement o + def visit_Arel_Visitors_MSSQL_RowNumber o, collector + collector << "ROW_NUMBER() OVER (ORDER BY " + inject_join(o.children, collector, ', ') << ") as _row_num" + end + + def visit_Arel_Nodes_SelectStatement o, collector if !o.limit && !o.offset - return super o + return super end - select_order_by = "ORDER BY #{o.orders.map { |x| visit x }.join(', ')}" unless o.orders.empty? - is_select_count = false - sql = o.cores.map { |x| - core_order_by = select_order_by || determine_order_by(x) + o.cores.each { |x| + core_order_by = row_num_literal determine_order_by(o.orders, x) if select_count? x - x.projections = [row_num_literal(core_order_by)] + x.projections = [core_order_by] is_select_count = true else - x.projections << row_num_literal(core_order_by) + x.projections << core_order_by end + } - visit_Arel_Nodes_SelectCore x - }.join + if is_select_count + # fixme count distinct wouldn't work with limit or offset + collector << "SELECT COUNT(1) as count_id FROM (" + end + + collector << "SELECT _t.* FROM (" + collector = o.cores.inject(collector) { |c,x| + visit_Arel_Nodes_SelectCore x, c + } + collector << ") as _t WHERE #{get_offset_limit_clause(o)}" - sql = "SELECT _t.* FROM (#{sql}) as _t WHERE #{get_offset_limit_clause(o)}" - # fixme count distinct wouldn't work with limit or offset - sql = "SELECT COUNT(1) as count_id FROM (#{sql}) AS subquery" if is_select_count - sql + if is_select_count + collector << ") AS subquery" + else + collector + end end def get_offset_limit_clause o @@ -46,26 +61,29 @@ module Arel end end - def determine_order_by x - unless x.groups.empty? - "ORDER BY #{x.groups.map { |g| visit g }.join ', ' }" + def determine_order_by orders, x + if orders.any? + orders + elsif x.groups.any? + x.groups else - "ORDER BY #{find_left_table_pk(x.froms)}" + pk = find_left_table_pk(x.froms) + pk ? [pk] : [] end end def row_num_literal order_by - Nodes::SqlLiteral.new("ROW_NUMBER() OVER (#{order_by}) as _row_num") + RowNumber.new order_by end def select_count? x x.projections.length == 1 && Arel::Nodes::Count === x.projections.first end - # fixme raise exception of there is no pk? - # fixme!! Table.primary_key will be depricated. What is the replacement?? + # FIXME raise exception of there is no pk? + # FIXME!! Table.primary_key will be deprecated. What is the replacement?? def find_left_table_pk o - return visit o.primary_key if o.instance_of? Arel::Table + return o.primary_key if o.instance_of? Arel::Table find_left_table_pk o.left if o.kind_of? Arel::Nodes::Join end end |