数据表格式:
id year month
110108196802226415 2020 1
110108196802226415 2020 2
110108196802226415 2020 3
110108196802226415 2020 4
110108196802226415 2020 5
110108196802226415 2020 7
110108196802226415 2020 8
110108196802226415 2020 9
110108196802226415 2020 10
110108196802226415 2020 11
想要在oracle中取得下面数据格式,月份连续时取连续值的第一个
结果集
id year month beginMonth
110108196802226415 2020 1 1
110108196802226415 2020 2 1
110108196802226415 2020 3 1
110108196802226415 2020 4 1
110108196802226415 2020 5 1
110108196802226415 2020 7 7
110108196802226415 2020 8 7
110108196802226415 2020 9 7
110108196802226415 2020 10 7
110108196802226415 2020 11 7