Class: Arel::Visitors::Derby

Inherits:
ToSql
  • Object
show all
Defined in:
lib/arel/visitors/derby.rb

Instance Method Summary collapse

Instance Method Details

#visit_Arel_Nodes_Limit(o, a = nil) ⇒ Object 



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# File 'lib/arel/visitors/derby.rb', line 16

def visit_Arel_Nodes_Limit o, a = nil
  "FETCH FIRST #{limit_for(o)} ROWS ONLY"
end

#visit_Arel_Nodes_Lock(o, a = nil) ⇒ Object

This generates SELECT...FOR UPDATE, but it will only work if the current transaction isolation level is set to SERIALIZABLE. Otherwise, locks aren't held for the entire transaction.



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# File 'lib/arel/visitors/derby.rb', line 27

def visit_Arel_Nodes_Lock o, a = nil
  do_visit o.expr, a
end

#visit_Arel_Nodes_Offset(o, a = nil) ⇒ Object 



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# File 'lib/arel/visitors/derby.rb', line 20

def visit_Arel_Nodes_Offset o, a = nil
  "OFFSET #{do_visit o.value, a} ROWS"
end

#visit_Arel_Nodes_SelectStatement(o, a = nil) ⇒ Object 



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# File 'lib/arel/visitors/derby.rb', line 7

def visit_Arel_Nodes_SelectStatement o, a = nil
  sql = o.cores.map { |x| do_visit(x, a) }.join
  sql << " ORDER BY #{o.orders.map { |x| visit x }.join(', ')}" unless o.orders.empty?
  sql << " #{do_visit o.offset, a}" if o.offset
  sql << " #{do_visit o.limit, a}" if o.limit
  sql << " #{do_visit o.lock, a}" if o.lock
  sql
end