小编Ale*_*lex的帖子

如何收集所有角色(系统 - >权限 - >角色)和具有此角色的用户？

谢谢.

我有一个脚本,它计算所有表数据的中值:

SELECT avg(t1.price) as median_val FROM (
SELECT @rownum:=@rownum+1 as `row_number`, d.price
  FROM mediana d,  (SELECT @rownum:=0) r
  WHERE 1
  ORDER BY d.price
) as t1, 
(
  SELECT count(*) as total_rows
  FROM mediana d
  WHERE 1
) as t2
AND t1.row_number>=total_rows/2 and t1.row_number<=total_rows/2+1;

现在我需要得到不是所有表值的中值,而是按日期分组.可能吗？http://sqlfiddle.com/#!2/7cf27 - 结果我将得到2013-03-06 - 1.5,2013-03-05 - 3.5.

如何通过付款方式'checkmo'获取订单？我可以使用addFieldToFilter函数吗？

谢谢.

我需要使用Haskell在列表上生成传递闭包.

到目前为止我得到了这个:

import Data.List
qq [] = []
qq [x] = [x]
qq x = vv (sort x)

vv (x:xs) = [x] ++ (member [x] [xs]) ++  (qq xs)

member x [y] = [(x1, y2) | (x1, x2) <- x, (y1, y2) <- qq (y), x2 == y1]

输出1:

*Main> qq [(1,2),(2,3),(3,4)]
[(1,2),(1,3),(1,4),(2,3),(2,4),(3,4)]

输出2:

*Main> qq [(1,2),(2,3),(3,1)]
[(1,2),(1,3),(1,1),(2,3),(2,1),(3,1)]

问题在于第二次输出.它不是在新生成的列表上检查额外的传递闭包,而是返回结果.

为了原型haskell代码,我使用了这个Python代码:

def transitive_closure(angel):
    closure = set(angel)
    while True:
        new_relations = set((x,w) for x,y in closure for q,w in closure …