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CONNECT BY 递归查询树形结构关系
命令格式如下：
SELECT ….. CONNECT BY {PRIOR 列名1=列名2|列名1=PRIOR 列名2}
[START WITH]；
其中：CONNECT BY子句说明每行资料将是按层次顺序检索，并规定将表中的资料连入树形结构的关系中。
0PRIORY运算符必须放置在连接关系的两列中的某一个的前面。对于节点间的父子关系，PRIOR去处符在一侧表示父节点，
在别一侧表示子节点，从而确定查找权结构的顺序是自顶向下还是自底向上。在连接关系中，除了可以使用列名外，
还允许使用列运算式。START WITH 子句为可选项，用来标识哪个节点作为查找树型结构的根节点。
例子：
从Root往树末梢递归
select * from TBL_TEST start with id=1 connect by prior id = pid
从末梢往树ROOT递归
select * from TBL_TEST start with id=5 connect by prior pid = id
可通过level 关键字查询所在层次
select a.*,level from TBL_TEST start with id=1 connect by prior id = pid
通过子节点获得顶节点
select FIRST_VALUE(deptid) OVER (ORDER BY LEVEL DESC ROWS UNBOUNDED PRECEDING) AS firstdeptid from persons.dept start with deptid=76 connect by prior paredeptid=deptid
下拉中用数据源取年份时，可用如下方式写：
select * from
(select rownum,to_char(add_months(sysdate, 4), 'yyyy') - rownum
from dual connect by rownum<5);
递归删除树节点
/**
* 递归删除所有子节点
*/
public void removeNode(Long areaId){
List<Object> args = new ArrayList<Object>();
args.add(areaId);
StringBuffer sql = new StringBuffer("");
sql.append(" delete from CDH_NEWRBT_AREA t where t.area_id in ");
sql.append(" ( ");
sql.append(" select a.area_id from CDH_NEWRBT_AREA a ");
sql.append(" start with a.area_id = ? ");
sql.append(" connect by prior a.area_id = a.parent_id");
sql.append(" ) ");
log.info(sql.toString());
this.executeUpdateSql(sql.toString(), args);
}
public int executeUpdateSql(final String sql, final List<Object> args){
return (Integer)getHibernateTemplate().execute(new HibernateCallback() {
public Object doInHibernate(Session session) throws HibernateException {
Query query = session.createSQLQuery(sql);
if (args != null && args.size() > 0) {
Object[] values = args.toArray();
for (int i = 0; i < values.length; i++) {
query.setParameter(i, values[i]);
}
}
return query.executeUpdate();
}
});
}
oracle :
select t.organization_id from ims_rt_organization t
connect by prior t.organization_id = t.super_organization_id
start with t.super_organization_id=#value#
//得到本组织所有的上级组织ID
select t.super_organization_id from ims_rt_organization t
connect by prior t.super_organization_id = t.organization_id
start with t.organization_id=#value#
db2 :
with b(organization_id) as (
select organization_id
from ims_rt_organization where organization_id = #value#
union all
select a.organization_id
from ims_rt_organization as a,b
where b.organization_id = a.super_organization_id )
select * from b
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