Activerecord - 執行復雜查詢

Question

我想在「Activerecord」中執行以下查詢。我怎樣才能做到這一點？請幫我..

query = "SELECT rc.constraint_schema||'.'||tc.table_name AS table_name, kcu.column_name FROM information_schema.referential_constraints AS rc JOIN information_schema.table_constraints AS tc USING(constraint_catalog,constraint_schema,constraint_name) JOIN information_schema.key_column_usage AS kcu USING(constraint_catalog,constraint_schema,constraint_name) JOIN information_schema.key_column_usage AS ccu ON(ccu.constraint_catalog=rc.unique_constraint_catalog AND ccu.constraint_schema=rc.unique_constraint_schema AND ccu.constraint_name=rc.unique_constraint_name) WHERE ccu.table_catalog=\"#{connection_parameters['database']}\" AND ccu.table_schema=\"#{connection_parameters['schema_search_path']}\" AND ccu.table_name=\"#{tab}\" AND ccu.column_name=\"#{select}\"" 

Answer 1

你可以使用select_rows從模型方法中：

def some_method 
    query = "... big pile of SQL ..." 
    connection.select_rows(sql).each do |row| 
     table_name, column_name = *row 
     #... 
    end 
end