Generated order number

<the SELECT the above mentioned id = "getOrderNumber" resultType = "String"> 
   the SELECT order_sque.nextval 
   from Dual 
</ the SELECT> 
https://zhidao.baidu.com/question/129650627.html

 Dual: oracle is a virtual table, not real existence . 
SEQ_YX:. this is the developer's own played a "sequence" of the name, id number sequences are generally used to generate 
SEQ_YX.nextval is the next sequence of a value takes 

take, for example 
the current value of the sequence is 100, about the implementation of the above the statement will be taken to 101, then it will take to perform the 102, has been accumulating go 

For a detailed description of the sequence, you can check under the oracle of documents or re Baidu under ..