我正在创建以下输出，并且正在寻找一种基于前几个月结果预测 NULL 值的简单方法。我想说的是 - 如果值为 NULL，则计算过去 4 个月的平均增长并将其应用于该月数。
请问有什么办法可以在SQL中做到这一点吗？谢谢！
Year month N30 N3 N6 N12
2013 1 £23.62 £43.70 £68.96 £104.67
2013 2 £26.13 £50.05 £84.58 £153.97
2013 3 £21.39 £41.16 £62.07 £97.59
2013 4 £21.88 £43.62 £62.66 £94.08
2013 5 £19.06 £31.97 £51.56 £78.86
2013 6 £24.88 £60.32 £79.72 £112.66
2013 7 £16.36 £34.64 £59.30 £85.83
2013 8 £18.98 £36.75 £52.99 £76.60
2013 9 £15.96 £33.70 £57.15 £98.41
2013 10 £15.44 £34.07 £51.69 £75.03
2013 11 £16.88 £38.23 £58.21 £93.72
2013 12 £9.61 £27.78 £46.04 £76.72
2014 1 £16.39 £34.63 £50.47 £87.18
2014 2 £7.59 £26.34 £43.65 NULL
2014 3 £7.22 £21.90 £41.99 NULL
2014 4 £6.50 £22.57 £46.98 NULL
2014 5 £2.80 £23.26 £43.24 NULL
2014 6 £4.96 £27.18 £49.08 NULL
2014 7 £10.06 £35.43 £71.86 NULL
2014 8 £7.53 £31.20 NULL NULL
2014 9 £10.60 £29.21 NULL NULL
2014 10 £2.19 £23.38 NULL NULL
2014 11 £7.82 NULL NULL NULL