Question 2: Every data structure in DW contains time element. Why? Solution Data Warehouse enables organizations to slice and dice data over a period of time to make business decisions. To make the intelligent business decisions, it is required to take a look at the trends of the operational data. Date dimension is important and it may be required to analyse based on for example -Year -Quarter -Month -Dayoftheweek -Timeoftheday -Typeof thedate -Month, etc... The time fields may be explicit or implicit. The explicit fields about time make queries to run faster and provides efficient drill-down facilities. Operational database is mainly for current transactions, where as having time element is important in DW data structures to analyse the past data which helps to forecast the future..