In Java, write a mini version of the translator from SQL to the MongoDB shell commands.
The input translator receives a string with an SQL query and returns a string with the MongoDB command.
Example SELECT * FROM sales LIMIT 10 -> db.sales.find({}).limit(10)
- It is enough to support only SELECT queries
- The list of columns in SELECT must be translated into the projection of the find command:
SELECT name, surname FROM collection -> db.collection.find({}, {name: 1, surname: 1}) - SKIP/OFFSET and LIMIT are translated into the corresponding functions of MongoDB cursors:
SELECT * FROM collection OFFSET 5 LIMIT 10 -> db.collection.find({}).skip(5).limit(10) - Predicates in WHERE turn into predicates of the find command:
SELECT * FROM customers WHERE age > 22 -> db.customers.find({age: {$gt: 22}}) - Implement only comparison operations: = <> <>. If there are several predicates, then they are connected by the AND operation
Do not forget to write tests.