Moved adding of limit on deletion and adding of limit on update condi…

…tions to GenericCompiler, to provide flexibility to handle db specifics

Signed-off-by: Emilio Tagua <miloops@gmail.com>

lib/arel/engines/sql/compilers/ibm_db_compiler.rb

@@ -0,0 +1,62 @@
+# +-----------------------------------------------------------------------+
+# |                                                                       |
+# | Copyright (c) 2010 IBM Corporation                                    |
+# |                                                                       |
+# | Permission is hereby granted, free of charge, to any person obtaining |
+# | a copy of this software and associated documentation files (the       |
+# | "Software"), to deal in the Software without restriction, including   |
+# | without limitation the rights to use, copy, modify, merge, publish,   |
+# | distribute, sublicense, and/or sell copies of the Software, and to    |
+# | permit persons to whom the Software is furnished to do so, subject to |
+# | the following conditions:                                             |
+# |                                                                       |
+# | The above copyright notice and this permission notice shall be        |
+# | included in all copies or substantial portions of the Software.       |
+# |                                                                       |
+# | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       |
+# | EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    |
+# | MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.|
+# | IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR      |
+# | ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION           |
+# | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION |
+# | WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.       |
+# |                                                                       |
+# +-----------------------------------------------------------------------+
+
+#
+#  Author: Praveen Devarao <praveendrl@in.ibm.com>
+#
+
+module Arel
+  module SqlCompiler
+    class IBM_DBCompiler < GenericCompiler
+
+      def select_sql
+        query = build_query \
+          "SELECT     #{select_clauses.join(', ')}",
+          "FROM       #{from_clauses}",
+          (joins(self)                                   unless joins(self).blank? ),
+          ("WHERE     #{where_clauses.join(" AND ")}"    unless wheres.blank?      ),
+          ("GROUP BY  #{group_clauses.join(', ')}"       unless groupings.blank?   ),
+          ("HAVING    #{having_clauses.join(', ')}"      unless havings.blank?     ),
+          ("ORDER BY  #{order_clauses.join(', ')}"       unless orders.blank?      )
+          engine.add_limit_offset!(query,{:limit=>taken,:offset=>skipped}) unless taken.blank?
+          query << "#{locked}" unless locked.blank?
+          query
+      end
+
+      def limited_update_conditions(conditions, taken)
+        quoted_primary_key = engine.quote_table_name(primary_key)
+        update_conditions = "WHERE #{quoted_primary_key} IN (SELECT #{quoted_primary_key} FROM #{engine.connection.quote_table_name table.name} #{conditions} " #Note: - ')' not added, limit segment is to be appended
+        engine.add_limit_offset!(update_conditions,{:limit=>taken,:offset=>nil})
+        update_conditions << ")" # Close the sql segment
+        update_conditions
+      end
+
+      def add_limit_on_delete(taken)
+        "" # Limiting the number of rows to be deleted is not supported by IBM_DB
+      end
+
+    end
+  end
+end

lib/arel/engines/sql/relations/compiler.rb

@@ -21,11 +21,16 @@ def select_sql
           ("#{locked}"                                   unless locked.blank?)
       end
 
-      def limited_update_conditions(conditions)
+      def limited_update_conditions(conditions, taken)
+        conditions << " LIMIT #{taken}"
         quoted_primary_key = engine.quote_table_name(primary_key)
         "WHERE #{quoted_primary_key} IN (SELECT #{quoted_primary_key} FROM #{engine.connection.quote_table_name table.name} #{conditions})"
       end
 
+      def add_limit_on_delete(taken)
+        "LIMIT #{taken}"
+      end
+
       def supports_insert_with_returning?
         false
       end

lib/arel/engines/sql/relations/writes.rb

@@ -5,7 +5,7 @@ def to_sql
         "DELETE",
         "FROM #{table_sql}",
         ("WHERE #{wheres.collect(&:to_sql).join(' AND ')}" unless wheres.blank? ),
-        ("LIMIT #{taken}"                                  unless taken.blank?  )
+        (compiler.add_limit_on_delete(taken)               unless taken.blank?  )
     end
   end
 
@@ -68,9 +68,7 @@ def build_update_conditions_sql
       conditions << " ORDER BY #{order_clauses.join(', ')}" unless orders.blank?
 
       unless taken.blank?
-        conditions << " LIMIT #{taken}"
-
-        conditions = compiler.limited_update_conditions(conditions)
+        conditions = compiler.limited_update_conditions(conditions,taken)
       end
 
       conditions