在postgresql11.0中我有下表

min age      max age
1 Month      12 Months
1 Year       16 Years
1 Day        365 Days
365 Days     369 Days
N/A          N/A
NULL         NULL

我想把这些值转换成年份。我正在提取数字后面的字符串，检查它是'years'、'months'还是'days'，然后将字符串前面的数字转换为year。
我尝试了以下查询：

update tbl
set min_age = 
        case 
                when substring(min_age, '^\d+\s(.*)') ~* 'Month'
                then abs(substring(min_age, '^(\d+)\s.*')/12)
                when substring(min_age, '^\d+\s(.*)') ~* 'Months'
                then abs(substring(min_age, '^(\d+)\s.*')/12)
                when substring(min_age, '^\d+\s(.*)') ~* 'Day'
                then abs(substring(min_age, '^(\d+)\s.*')/365)
                when substring(min_age, '^\d+\s(.*)') ~* 'Days'
                then abs(substring(min_age, '^(\d+)\s.*')/365)
                when substring(min_age, '^\d+\s(.*)') ~* 'Year'
                then abs(substring(min_age, '^(\d+)\s.*'))
                when substring(min_age, '^\d+\s(.*)') ~* 'Years'
                then abs(substring(min_age, '^(\d+)\s.*'))
        end ;

update tbl
set max_age = case
                when substring(min_age, '^\d+\s(.*)') ~* 'Month'
                then abs(substring(min_age, '^(\d+)\s.*')/12)
                when substring(min_age, '^\d+\s(.*)') ~* 'Months'
                then abs(substring(min_age, '^(\d+)\s.*')/12)
                when substring(min_age, '^\d+\s(.*)') ~* 'Day'
                then abs(substring(min_age, '^(\d+)\s.*')/365)
                when substring(min_age, '^\d+\s(.*)') ~* 'Days'
                then abs(substring(min_age, '^(\d+)\s.*')/365)
                when substring(min_age, '^\d+\s(.*)') ~* 'Year'
                then abs(substring(min_age, '^(\d+)\s.*'))
                when substring(min_age, '^\d+\s(.*)') ~* 'Years'
                then abs(substring(min_age, '^(\d+)\s.*'))
           end

预期输出为：

min age       max age
0             1
1             16
0             1
1             1
N/A           N/A
NULL          NULL

非常感谢您的帮助。