Database format:

Want to query result:


In case the when can I do, but the results will be three lines, have a line can be generated

CodePudding user response:

Try left the join

CodePudding user response:

 select 
At1. As A '2019 A' 
At1. B as' 2019 B ', 
At1. C as' 2019 C, 
At2. As A '2018 A' 
At2. B as' 2018 B ', 
At2. C as' 2018 C, 
At3. As A '2017 A' 
At3. B as' 2017 B ', 
At3. C as' 2017 C, 
At4. As A '2016 A' 
At4. B as' 2016 B ', 
At4. C as a '2016 C' 
From the at the as at1 
Left the join at the as at2 on at1. Datetime & lt;> At2. Datetime 
Left the join at the as at3 on at2. Datetime & lt;> At3. Datetime 
Left the join at the as at4 on at3. Datetime & lt;> At4. Datetime 
Where at1) Datetime=2019 and at2) Datetime=2018 and at3 Datetime=2017 and at4. Datetime=2016 

CodePudding user response:

Understand, thank you for your brother