MSSQL PatIndex활용 문자열 혼합된 데이터 일괄 업데이트

PatIndex('%[^0-9]%' 로 nums의 3자리가 int형인지 검사하고(참이면 3, 아니면 0)
자기 자신 db를 조인해서 일괄업데이트진행.

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Update db set ClsNum == aa
from db as A
Join
(  Select aa, ids from(
       Select nums as aa, ids from(
          Select PatIndex('%[^0-9]%', left(VarNums,3) ) as nums , * from db where len(VarNums)>3
        ) as AB where aa = 3
     ) as ABB
) AS B on A.ids = B.ids
where len(VarNums)>4 and len(ClsNum)<3

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