Monica Shiralkar wrote:
Why have they designed noSQL databases in such a way that they do not have a capability for Query using SQL statements.
In my opinion, it is probably related to the company knowing their potential customer base. Most customers switching to them would probably want the performance gained from how the database is stored, used, etc. And while in theory, it is possible to write an SQL layer above it, which would likely be lacking in performance due to structural differences.... So, since any potential customer needing to micro-manage those details, are likely looking for performance, they will be unlikely use the SQL API anyway.
Having said that, there are some noSQL databases that provide an SQL API -- which arguably changes the meaning of noSQL to mean "Not Only SQL" database...
Most of the NOSQL DBs like MongoDB provide a querying API. Without a querying API, there is no use of a DB. It doesn't necessarily needs to be SQL queries for all databases. RDBMS needs SQL as the latter is meant to query relational data.
NOSQL dbs are of varied types: Key value, document, etc. and SQL may not be the ideal way to query them all. Hence the need for a different mechanism to query them.