How can I get all possible flights between two cities?

I have a MySQL table called flight data as shown below:

Expected results:

• Bangalore to Chennai
• Bangalore to Delhi
• Bangalore to Kolkata
• Bangalore to Mumbai
• Chennai to Bangalore
• Chennai to Delhi
• Chennai to Kolkata
• Chennai to Mumbai
• Delhi to Chennai
• Delhi to Bangalore
• Delhi to Kolkata
• Delhi to Mumbai
• Kolkata to Chennai
• Kolkata to Delhi
• Kolkata to Bangalore
• Kolkata to Mumbai
• Mumbai to Chennai
• Mumbai to Delhi
• Mumbai to Kolkata
• Mumbai to Bangalore

not with the same city.