I have a table which contains data as follows:
create table journey( Src varchar(255), Dest varchar(255)) insert into journey values('Jaipur', 'Mumbai'), ('Mumbai', 'Jaipur'), ('Kolkata', 'Bangalore'), ('Bangalore', 'Indore'), ('Indore', 'Lucknow'), ('Lucknow', 'Indore')
I want a table which do not have Mumbai—>Jaipur as it is present already before being swapped. Similarly, Lucknow—>Indore is not required. All other entries must come as it is which is there in the existing table.
Can any body help.
Note: Table must not have any id or S.No. in the table.
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Answer
You can create a view
or use select
statement with not exists
to prevent duplicate journey :
select j.* from journey j where not exists (select 1 from journey j1 where j1.src = j.dest and j1.dest = j.src and j1.src < j.src and j1.dest > j.dest );