1. Write a query for merging two columns into one column
on conditional bases(i.e. I want to select Employee Name from
any of the column FullName or FirstName whichever is not null).
To query from two columns conditionally we need to use CASE operator that is provided by SQL Server. Following is the query which depicts how to retrieve conditional value into one column.
1. Define Data Warehouse.
Ans. A data warehouse is a relational database that is designed for query and analysis rather than for transaction processing. It usually contains historical data derived from transaction data, but it can include data from other sources.
2. Which are three layers in which data warehouse maintains it’s functions?
Ans. A data warehouse maintains its functions in staging, integration and access.
3. Can you elaborate it?
Ans. Staging: It is …