Use fully qualified database name when retrieving column definitions to support linked servers.

Author: Jippe Holwerda

lib/active_record/connection_adapters/sqlserver/schema_statements.rb

@@ -221,7 +221,7 @@ def initialize_native_database_types
 
         def column_definitions(table_name)
           identifier  = SQLServer::Utils.extract_identifiers(table_name)
-          database    = "#{identifier.database_quoted}." if identifier.database_quoted
+          database    = identifier.fully_qualified_database_quoted
           view_exists = schema_cache.view_exists?(table_name)
           view_tblnm  = table_name_or_views_table_name(table_name) if view_exists
           sql = %{
@@ -237,7 +237,7 @@ def column_definitions(table_name)
             columns.ordinal_position,
             CASE
               WHEN columns.DATA_TYPE IN ('nchar','nvarchar','char','varchar') THEN columns.CHARACTER_MAXIMUM_LENGTH
-              ELSE COL_LENGTH('#{database}'+columns.TABLE_SCHEMA+'.'+columns.TABLE_NAME, columns.COLUMN_NAME)
+              ELSE COL_LENGTH('#{database}.'+columns.TABLE_SCHEMA+'.'+columns.TABLE_NAME, columns.COLUMN_NAME)
             END AS [length],
             CASE
               WHEN columns.IS_NULLABLE = 'YES' THEN 1
@@ -248,24 +248,24 @@ def column_definitions(table_name)
               ELSE NULL
             END AS [is_primary],
             c.is_identity AS [is_identity]
-            FROM #{database}INFORMATION_SCHEMA.COLUMNS columns
-            LEFT OUTER JOIN #{database}INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS TC
+            FROM #{database}.INFORMATION_SCHEMA.COLUMNS columns
+            LEFT OUTER JOIN #{database}.INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS TC
               ON TC.TABLE_NAME = columns.TABLE_NAME
               AND TC.CONSTRAINT_TYPE = N'PRIMARY KEY'
-            LEFT OUTER JOIN #{database}INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KCU
+            LEFT OUTER JOIN #{database}.INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KCU
               ON KCU.COLUMN_NAME = columns.COLUMN_NAME
               AND KCU.CONSTRAINT_NAME = TC.CONSTRAINT_NAME
               AND KCU.CONSTRAINT_CATALOG = TC.CONSTRAINT_CATALOG
               AND KCU.CONSTRAINT_SCHEMA = TC.CONSTRAINT_SCHEMA
-            INNER JOIN #{identifier.database_quoted}.sys.schemas AS s
+            INNER JOIN #{database}.sys.schemas AS s
               ON s.name = columns.TABLE_SCHEMA
               AND s.schema_id = s.schema_id
-            INNER JOIN #{identifier.database_quoted}.sys.objects AS o
+            INNER JOIN #{database}.sys.objects AS o
               ON s.schema_id = o.schema_id
               AND o.is_ms_shipped = 0
               AND o.type IN ('U', 'V')
               AND o.name = columns.TABLE_NAME
-            INNER JOIN #{identifier.database_quoted}.sys.columns AS c
+            INNER JOIN #{database}.sys.columns AS c
               ON o.object_id = c.object_id
               AND c.name = columns.COLUMN_NAME
             WHERE columns.TABLE_NAME = @0
@@ -299,7 +299,7 @@ def column_definitions(table_name)
               if default.nil? && view_exists
                 default = select_value "
                   SELECT c.COLUMN_DEFAULT
-                  FROM #{database}INFORMATION_SCHEMA.COLUMNS c
+                  FROM #{database}.INFORMATION_SCHEMA.COLUMNS c
                   WHERE c.TABLE_NAME = '#{view_tblnm}'
                   AND c.COLUMN_NAME = '#{views_real_column_name(table_name, ci[:name])}'".squish, 'SCHEMA'
               end

lib/active_record/connection_adapters/sqlserver/utils.rb

@@ -39,6 +39,10 @@ def server_quoted
             server ? quote(server) : server
           end
 
+          def fully_qualified_database_quoted
+            [server_quoted, database_quoted].compact.join(SEPARATOR)
+          end
+
           def to_s
             quoted
           end

test/cases/utils_test_sqlserver.rb

@@ -86,6 +86,14 @@ class UtilsTestSQLServer < ActiveRecord::TestCase
       SQLServer::Utils.extract_identifiers('[obj.name].[foo]').quoted.must_equal '[obj.name].[foo]'
     end
 
+    it 'can return fully qualified quoted table name' do
+      name = SQLServer::Utils.extract_identifiers('[server.name].[database].[schema].[object]')
+      name.fully_qualified_database_quoted.must_equal '[server.name].[database]'
+
+      name = SQLServer::Utils.extract_identifiers('server.database.schema.object')
+      name.fully_qualified_database_quoted.must_equal '[server].[database]'
+    end
+
   end
 
 end