https://bbs.csdn.net/topics/390480323
ISNUMERIC(size_long)=1
(IIF( ISNUMERIC(size_long)=1
AND ISNUMERIC(size_wide)=1
AND ISNUMERIC(size_high)=1 ,CONVERT(DECIMAL,size_high)+CONVERT(DECIMAL,size_long)+CONVERT(DECIMAL,size_wide),0)
原文：https://www.cnblogs.com/LuoEast/p/9067142.html