Oracle start with...connect by prior 实现递归查询

ewr212

基本语法：


    select ... fro
    where
    start with
    connect by ;  
      
    ：过滤条件，用于对返回的所有记录进行过滤。  
   ：查询结果重起始根结点的限定条件。  
   ：连接条


数据表结构如下：


    create table table_test(  
    priorId number,  
    id number,  
    name varchar(5),  
    description varchar(10)  
    );  


测试数据：


    insert into table_test(priorId,id,name,description) values(0,1,'f','f父类');  
    insert into table_test(priorId,id,name,description) values(1,2,'f1','f子类1');  
    insert into table_test(priorId,id,name,description) values(1,3,'f2','f子类2');  
    insert into table_test(priorId,id,name,description) values(0,4,'F','F父类');  
    insert into table_test(priorId,id,name,description) values(4,5,'F1','F子类1');  
    insert into table_test(priorId,id,name,description) values(4,6,'F2','F子类2');  



获取完整树：


    select * from table_test start with priorId = 0 connect by prior id = priorId;  


获取特定子树：


    select * from table_test start with id = 1 connect by prior id = priorId;  
    select * from table_test start with id = 4 connect by prior id = priorId;  


如果connect by prior中的prior被省略，则查询将不进行深层递归：


    select * from table_test start with priorId = 0 connect by id = priorId;  
    select * from table_test start with id = 1 connect by id = priorId;