SQL Server 2017

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create table test(SequenceId varchar(20));

insert into test values

('2-10-14')

,('2-8-15')

,('2-8-16')

,('2-17-21')

,('2-0-5')

,('4-1-10')

,('4-1-100')

;

select * from test

update test

set SequenceId=

concat(left(SequenceId,len(SequenceId)-charindex('-',reverse(SequenceId))+1)

,cast(cast(right(SequenceId,charindex('-',reverse(SequenceId))-1) as int)-1 as varchar)

);

select * from test;