There may be a Feature film (movie) without a Trialer.But there will be no trialer without a movie.similarly Data warehousing is a concept related to extracting client's business data and applying business processing features on that data according to user needs and finally loading the processed data into a database,this database is what we call a warehouse or data warehouse. After the completion of a data warehouse the business user ultimately want to view his data (a precise and summary data)but as a business person he may don't have knowledge of accessing a database( a computer person can access the database with SQL)..so there comes olap toos(which help that person to access the database )we can call these olap tools as Business Intelligence tools(Intelligence in sense they generate sql queries internally and provide lot of facilities and privileges for a reporting developers in formating the data and presenting it in a higly convenient manner). So data warehouse(movie) is a database and business intelligence tools(trialers) present the content of a database in an effecticient manner.