SQL Query - Please Help

Question

UserMaster

ID	UserName	CreatedBy	Flag
1	Ashok	Admin	1
2	Amit	Admin	1
3	Amita	Admin	1
4	Amrita	Admin	1
5	Sandhya	Admin	1

UserTransactions

ID	UserName	SerialNumber	CertifiedStatus	Certifiedon
1	Ashok	A1	1	1-JAN-2016
2	Ashok	A2	1	1-FEB-2016
3	Ashok	A3	0	3-MAR-2016
4	Amit	A4	0	1-APR-2016
5	Sandhya	A5	1	3-MAR-2016
6	Sandhya	A6	1	1-JAN-2016
7	Sandhya	A7	0	1-JAN-2016
8	Sandhya	A8	0	1-JAN-2016
9	Amit	A9	0	3-MAR-2016
10	Amit	A10	1	3-MAR-2016

Output –

There are total 5 users, out of which 3 users have entered details.

UserName	Total Transactions	Certified Status	Date
Ashok	3	True	3-MAR-2016 (Max date of transaction)
Amit	3	True	3-MAR-2016 (Max date of transaction)
Amita	0	False	Null
Amrita	0	False	Null
Sandhya	4	true	3-MAR-2016 (Max date of transaction)

UserName –

Total Transactions – total transactions made by user

Certified stauts – if number of transactions is more than 0, then true, if zero then false

Date – Max Date of transaction

Also, how to get min and max date in output variable from stored procedure in asp.net c#??

My stored procedure –

@MinDateOut varchar(max) output

Select @MinDateOut = min(t.CreatedOn) from UserTransactions t