如何在ｓｑｌ中查询ｘｍｌ字符串

今天第一次尝试用xpath去搜索ｘｍｌ字符串，把自己写的ｓｑｌ帖在下面，以后参考

 WITH XMLNAMESPACES (
2    'http://www.gamingstandards.com/s2s/schemas/v1.2.6/' AS s2s,
3    'http://s2s.igt.com/player-ext1/v1.0.0' as p1)
4 select cast(body as xml).value('(/s2s:s2sMessage/s2s:s2sBody/s2s:player/s2s:playerInfo/@p1:playerId)[1]','varchar(50)') from dbo.s2sOutBound_Complete 
5 where cast(body as xml).exist('/s2s:s2sMessage/s2s:s2sBody/s2s:player/s2s:playerInfo') =1