The first statement defines the relational index, and the second defines the XML index.
第一个语句定义关系索引，第二个语句定义xml索引。
2
Relational update feeds consist of a single SQL statement.
关系型更新数据源包含单个sql语句。
3
In addition to the restrictions above, for MQTs over non-relational nicknames, the SQL statement defining the MQT must be valid for the non-relational data sources involved.