麻烦你update3次吧。
update a set body= case LEN(body)-LEN(REPLACE(body,'</p>',''))>0 then STUFF(body, CAST (rand()*(len(body)-(CHARINDEX('</p>',REVERSE(body))-1) ) as int ),CHARINDEX('</p>',body),'</p> <img src="images/01.png">')
else STUFF(body, CAST (rand()*(len(body)-(CHARINDEX('</br>',REVERSE(body))-1) ) as int ),CHARINDEX('</br>',body),'</br> <img src="images/01.png">') end
from dede_addonarticle a where
LEN(body)-LEN(REPLACE(body,'</p>',''))>0 --出现过'</p>'
or (LEN(body)-LEN(REPLACE(body,'</br>',''))>0 --出现过'</br>'
andLEN(body)-LEN(REPLACE(body,'</p>',''))=0) -没出现过'</p>'