easyu-tree的数据sql_easyui中的tree对应的sql语句-优快云博客

本文介绍了一种使用SQL语句来动态设置树状结构中节点的打开或关闭状态的方法。通过一个案例展示了如何根据子节点数量判断父节点的状态，适用于构建如easyui-tree等组件的数据源。

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public String getTest(HttpServletRequest request)
	{
		String parentId = req.getValue(request, "parentId");//菜单id
		String sql = " select a.id,a.name text,a.superorId parentId,a.tree_level level,"
				+" (case (select count(id) from BT_CountryRelation b where b.superorId =a.id) when 0 then 'open' else 'closed' end) AS state "
				+" from bt_countryrelation a where a.tree_level=1 ";
		if(null != parentId && !"".equals(parentId)){
			sql = " select a.id,a.name text,a.superorId parentId,a.tree_level level, "
				+" (case (select count(id) from BT_CountryRelation b where b.superorId =a.id) when 0 then 'open' else 'closed' end) AS state "
				+"from bt_countryrelation a where a.superorId ='"+parentId+"'";
		}
		List <?> list = db.queryForList(sql);
		JSONArray array = JSONArray.fromObject(list);
		return array.toString();
	}

上述为easyui-tree 中的数据-重点是一句sql解决了叶子节点的打开关闭状态

只在sqlserver中试过

 select a.id,a.name text,a.superorId parentId,a.tree_level,
(case (select count(id) from BT_CountryRelation b where b.superorId =a.id) when 0 then 'open' else 'closed' end) AS state
 from bt_countryrelation a where a.superorId = 1