- SQL is structured query language
- It was first commercial language used in RDBMS
- SQL language is divided into multiple sub elements
- Data is not in one machine or even one network.
- Data can be any type public data and private data
- Huge volume of data so you cannot put it in one place.
- It is uncoordinated in time as well as space.
- It is not always nice, structured data that SQL was meant to handle.