limit 1
值得注意的地方,struct() 与 named_struct() 的不同:
struct("zhejiang","hangzhou","hubin","201210")
会被编译成这样的数据结构...的节点就被定死了:
named_struct('street',"zhejiang", 'city',"hangzhou", 'state',"hubin", 'zip',"201210")
编译过后就是...:
struct('street',"zhejiang", 'city',"hangzhou", 'state',"hubin", 'zip',"201210")
而这种结构正符合表中定义的数据类型