3 つの新しい行で 1 つの行を複製する必要があり、新しい行ごとにシーケンス番号 +1 を増やします
insert into t1 (column1,column2,column3,sequencecolumn)
( **row1
select *from t1 (column1,'101',column3,sequencecolumn)
(select max (sequencecolumn)+1 where column1 ='abc')
where column1 = 'abc'
)
( ***row2
select *from t1 (column1,'102',column3,sequencecolumn)
(select max (sequencecolumn)+1 where column1 ='abc')
where column1 = 'abc'
)
( ***row3
select *from t1 (column1,'103',column3,sequencecolumn)
(select max (sequencecolumn)+1 where column1 ='abc')
where column1 = 'abc'
)