SqlException 捕获架构中的错误

请任何人帮助我解决我的工作中发生的错误，这些错误现在让我发疯。我想知道它下面的架构元素是否正确，如果不是，请帮助我解决这个问题。我使用 C# 编程编写了代码来运行它，当我使用方法adapter.Fill(ds)输出时，输出给出如下错误：

SqlException catch："，"附近的语法错误

<xs:appinfo>
  <wang:relation parent="n_person" parentKey="login" child="n_address" childKey="person_id"/>
  <wang:relation parent="n_org" parentKey="name" child="n_address" childKey="org_id"/>
  <wang:directive sql="SELECT street, city, province, postcode, sid, NULL FROM s_address,    
     s_student WHERE s_address.aid = s_student.fk_add;"/>
  <wang:directive sql="SELECT street, city, province, postcode, pid, NULL FROM s_address, 
     s_professor WHERE s_address.aid = s_professor.fk_add;"/>
  <wang:directive sql="SELECT street, city, province, postcode, NULL, name FROM s_address,  
     s_department WHERE s_address.aid = s_department.fk_add;"/>
</xs:appinfo>