MySQL 8.0

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create table mytable (
	agent_id varchar(10), 
	travel_destination varchar(20), 
	customer_id varchar(10),
	date_of_booking date
);

insert into mytable values
	('A1001', 'Singapore', 'C1001', '2019-06-10'),
	('A1001', 'Singapore', 'C1001', '2019-06-11'),
	('A1001', 'Austin', 'C1001', '2019-06-12'),
	('A1001', 'Singapore', 'C1001', '2019-06-13'),
	('A1001', 'Singapore', 'C1001', '2019-06-14'),
	('A1001', 'Dehli', 'C1001', '2019-06-15')
;
select  * from mytable


agent_id
travel_destination
customer_id
date_of_booking


A1001
Singapore
C1001
2019-06-10

A1001
Singapore
C1001
2019-06-11

A1001
Austin
C1001
2019-06-12

A1001
Singapore
C1001
2019-06-13

A1001
Singapore
C1001
2019-06-14

A1001
Dehli
C1001
2019-06-15


select 
	agent_id,	
	travel_destination,
	min(date_of_booking) first_date_of_booking,
	max(date_of_booking) max_date_of_booking
from (
	select 
		t.*,
		row_number() 
			over(partition by agent_id order by date_of_booking) rn1,
		row_number() 
			over(partition by agent_id, travel_destination order by date_of_booking) rn2
	from mytable t
) t
group by 
	agent_id, 
	rn1 - rn2,
	travel_destination
order by min(date_of_booking)


agent_id
travel_destination
first_date_of_booking
max_date_of_booking


A1001
Singapore
2019-06-10
2019-06-11

A1001
Austin
2019-06-12
2019-06-12

A1001
Singapore
2019-06-13
2019-06-14

A1001
Dehli
2019-06-15
2019-06-15

agent_id	travel_destination	customer_id	date_of_booking
A1001	Singapore	C1001	2019-06-10
A1001	Singapore	C1001	2019-06-11
A1001	Austin	C1001	2019-06-12
A1001	Singapore	C1001	2019-06-13
A1001	Singapore	C1001	2019-06-14
A1001	Dehli	C1001	2019-06-15