diff options
| -rw-r--r-- | README.markdown | 2 | ||||
| -rw-r--r-- | lib/arel/visitors/oracle.rb | 6 | ||||
| -rw-r--r-- | spec/crud_spec.rb | 2 | ||||
| -rw-r--r-- | spec/visitors/oracle_spec.rb | 10 |
4 files changed, 17 insertions, 3 deletions
diff --git a/README.markdown b/README.markdown index 10d3f0a021..ab05e1245a 100644 --- a/README.markdown +++ b/README.markdown @@ -60,7 +60,7 @@ What are called `LIMIT` and `OFFSET` in SQL are called `take` and `skip` in Arel users.group(users[:name]) # => SELECT * FROM users GROUP BY name -The best property of the Relational Algebra is its "composability", or closure under all operations. For example, to select AND project, just "chain" the method invocations: +The best property of the Relational Algebra is its "composability", or closure under all operations. For example, to restrict AND project, just "chain" the method invocations: users \ .where(users[:name].eq('amy')) \ diff --git a/lib/arel/visitors/oracle.rb b/lib/arel/visitors/oracle.rb index 659b75f16d..c691ce294e 100644 --- a/lib/arel/visitors/oracle.rb +++ b/lib/arel/visitors/oracle.rb @@ -6,7 +6,9 @@ module Arel def visit_Arel_Nodes_SelectStatement o o = order_hacks(o) - if o.limit && o.orders.empty? && !o.offset + # 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 ) @@ -31,7 +33,7 @@ module Arel eosql end - if o.limit && !o.orders.empty? + if o.limit o = o.dup limit = o.limit o.limit = nil diff --git a/spec/crud_spec.rb b/spec/crud_spec.rb index 3485df6685..36b2a0b4e4 100644 --- a/spec/crud_spec.rb +++ b/spec/crud_spec.rb @@ -1,3 +1,5 @@ +require 'spec_helper' + module Arel class FakeCrudder < SelectManager class FakeEngine diff --git a/spec/visitors/oracle_spec.rb b/spec/visitors/oracle_spec.rb index cdf0e3427f..93ade3ef3c 100644 --- a/spec/visitors/oracle_spec.rb +++ b/spec/visitors/oracle_spec.rb @@ -71,6 +71,16 @@ module Arel } end + it 'creates a subquery when there is DISTINCT' do + stmt = Nodes::SelectStatement.new + stmt.cores.first.projections << Nodes::SqlLiteral.new('DISTINCT id') + stmt.limit = 10 + sql = @visitor.accept stmt + sql.should be_like %{ + SELECT * FROM (SELECT DISTINCT id) WHERE ROWNUM <= 10 + } + end + it 'creates a different subquery when there is an offset' do stmt = Nodes::SelectStatement.new stmt.limit = 10 |