当值高于先前值时选择范围

时间：2014-01-07 21:53:18

标签： mysql trend forex

如何获取值高于之前值的所有记录。 例如，下表中的第一个范围从id 1开始，以id 6结束，下一个范围是7到10，等等...... 

id  Open
1   1.30077
2   1.30088
3   1.30115
4   1.30132
5   1.30135
6   1.30144
7   1.30132
8   1.30137
9   1.30152
10  1.30158
11  1.30149
12  ...

3 个答案:

答案 0 :(得分：2)

您的样本数据

USE test
DROP TABLE IF EXISTS rangedata;
CREATE TABLE rangedata
(
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  open FLOAT
) ENGINE=MyISAM;
INSERT INTO rangedata (open) VALUES
(1.30077),(1.30088),(1.30115),(1.30132),
(1.30135),(1.30144),(1.30132),(1.30137),
(1.30152),(1.30158),(1.30149),
(1.30077),(1.30088),(1.30115),(1.30132),
(1.30135),(1.30144),(1.30132),(1.30137),
(1.30152),(1.30158),(1.30149),
(1.30077),(1.30088),(1.30115),(1.30132),
(1.30135),(1.30144),(1.30132),(1.30137),
(1.30152),(1.30158),(1.30149);

您的示例数据已加载

mysql>     USE test
Database changed
mysql>     DROP TABLE IF EXISTS rangedata;
Query OK, 0 rows affected (0.01 sec)

mysql>     CREATE TABLE rangedata
    ->     (
    ->       id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    ->       open FLOAT
    ->     ) ENGINE=MyISAM;
Query OK, 0 rows affected (0.09 sec)

mysql>     INSERT INTO rangedata (open) VALUES
    ->     (1.30077),(1.30088),(1.30115),(1.30132),
    ->     (1.30135),(1.30144),(1.30132),(1.30137),
    ->     (1.30152),(1.30158),(1.30149),
    ->     (1.30077),(1.30088),(1.30115),(1.30132),
    ->     (1.30135),(1.30144),(1.30132),(1.30137),
    ->     (1.30152),(1.30158),(1.30149),
    ->     (1.30077),(1.30088),(1.30115),(1.30132),
    ->     (1.30135),(1.30144),(1.30132),(1.30137),
    ->     (1.30152),(1.30158),(1.30149);
Query OK, 33 rows affected (0.00 sec)
Records: 33  Duplicates: 0  Warnings: 0

mysql>

QUERY USING JOINS

这是LEFT JOIN查询

SET @grp = 1;
SELECT A.open prev,(@grp:=@grp+IF(A.open<B.open,1,0)) group_number
FROM rangedata A LEFT JOIN rangedata B ON A.id= B.id+1;

这是它的输出

mysql> SELECT A.open prev,(@grp:=@grp+IF(A.open<B.open,1,0)) group_number
    -> FROM rangedata A LEFT JOIN rangedata B ON A.id= B.id+1;
+---------+--------------+
| prev    | group_number |
+---------+--------------+
| 1.30088 |            1 |
| 1.30115 |            1 |
| 1.30132 |            1 |
| 1.30135 |            1 |
| 1.30144 |            1 |
| 1.30132 |            2 |
| 1.30137 |            2 |
| 1.30152 |            2 |
| 1.30158 |            2 |
| 1.30149 |            3 |
| 1.30077 |            4 |
| 1.30088 |            4 |
| 1.30115 |            4 |
| 1.30132 |            4 |
| 1.30135 |            4 |
| 1.30144 |            4 |
| 1.30132 |            5 |
| 1.30137 |            5 |
| 1.30152 |            5 |
| 1.30158 |            5 |
| 1.30149 |            6 |
| 1.30077 |            7 |
| 1.30088 |            7 |
| 1.30115 |            7 |
| 1.30132 |            7 |
| 1.30135 |            7 |
| 1.30144 |            7 |
| 1.30132 |            8 |
| 1.30137 |            8 |
| 1.30152 |            8 |
| 1.30158 |            8 |
| 1.30149 |            9 |
| 1.30077 |            9 |
+---------+--------------+
33 rows in set (0.01 sec)

QUERY WITHOUT JOINS

使用用户定义的变量，您只需监控每一行，并查看前一个值何时更大。准备好查询？这是：

SET @prev = '0.00000';
SET @grp = 1;
SELECT id,open,(@grp:=@grp+increasing) group_number FROM
(SELECT id,open,IF(@prev<=open,0,1) increasing,(@prev:=open) FROM rangedata) A;

以下是您的示例数据三倍：

这是查询的执行：

mysql> SET @prev = '0.00000';
Query OK, 0 rows affected (0.00 sec)

mysql> SET @grp = 1;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT id,open,(@grp:=@grp+increasing) group_number FROM
    -> (SELECT id,open,IF(@prev<=open,0,1) increasing,(@prev:=open) FROM rangedata) A;
+----+---------+--------------+
| id | open    | group_number |
+----+---------+--------------+
|  1 | 1.30077 |            1 |
|  2 | 1.30088 |            1 |
|  3 | 1.30115 |            1 |
|  4 | 1.30132 |            1 |
|  5 | 1.30135 |            1 |
|  6 | 1.30144 |            1 |
|  7 | 1.30132 |            2 |
|  8 | 1.30137 |            2 |
|  9 | 1.30152 |            2 |
| 10 | 1.30158 |            2 |
| 11 | 1.30149 |            3 |
| 12 | 1.30077 |            4 |
| 13 | 1.30088 |            4 |
| 14 | 1.30115 |            4 |
| 15 | 1.30132 |            4 |
| 16 | 1.30135 |            4 |
| 17 | 1.30144 |            4 |
| 18 | 1.30132 |            5 |
| 19 | 1.30137 |            5 |
| 20 | 1.30152 |            5 |
| 21 | 1.30158 |            5 |
| 22 | 1.30149 |            6 |
| 23 | 1.30077 |            7 |
| 24 | 1.30088 |            7 |
| 25 | 1.30115 |            7 |
| 26 | 1.30132 |            7 |
| 27 | 1.30135 |            7 |
| 28 | 1.30144 |            7 |
| 29 | 1.30132 |            8 |
| 30 | 1.30137 |            8 |
| 31 | 1.30152 |            8 |
| 32 | 1.30158 |            8 |
| 33 | 1.30149 |            9 |
+----+---------+--------------+
33 rows in set (0.00 sec)

关键在于：每次出现一个新的组号时，都会告诉您下一个值。

请注意输出对于两个查询都是同等的

CAVEAT ：如果prev和open之间存在一些浮点问题，则第二个查询不是完美的解决方案。如果这些彼此非常接近，那可能就不对了。这是编写存储过程之外的最佳尝试。

答案 1 :(得分：0)

可以使用此查询对范围进行编号：

SELECT id, open, range_number
FROM( 
  SELECT *,
         if(@lastopen<open,@grp,@grp:=@grp+1) range_number,
         @lastopen:=open
  FROM table1,
  (select @lastopen:=null,@grp:=0) qqq
  ORDER BY id
) qqq;

演示：http://www.sqlfiddle.com/#!2/b1bb8/9 

| ID |           OPEN | RANGE_NUMBER |
|----|----------------|--------------|
|  1 | 1.300770044327 |            1 |
|  2 | 1.300879955292 |            1 |
|  3 | 1.301149964333 |            1 |
|  4 | 1.301319956779 |            1 |
|  5 |  1.30134999752 |            1 |
|  6 | 1.301440000534 |            1 |
|  7 | 1.301319956779 |            2 |
|  8 | 1.301370024681 |            2 |
|  9 | 1.301519989967 |            2 |
| 10 |  1.30157995224 |            2 |
| 11 | 1.301489949226 |            3 |

答案 2 :(得分：0)

SELECT startid,MAX(id) FROM (
    SELECT 
       @currentid := IF(@previous <= open,@currentid,id) as startid,
       @previous := open,
       id
    FROM ranges 
    JOIN (SELECT @currentid := MIN(id), @previous := MIN(open) FROM ranges) as variables
    ORDER BY id) runningscan
GROUP BY startid ORDER BY startid + 0;

在SQLFiddle上看到这个：http://sqlfiddle.com/#!2/e3cea/3

它的作用是：在runningscan子查询中，它会在表中运行一次，如果open大于或小于前一个open（存储在@previous变量中，则保持点击这会给你一个包含所有id的列表，并且id会启动一个中断的更高（或相等）'run'。从那里，我们只需要找到一个起始id的最高id，所以我们把它放在子查询中一个简单的max构造。id列中的差距没有问题。如果单行不能是一个范围（即：open连续降低两次或更多），请添加外部查询中的WHERE startid < id子句。如果您需要的最小行数范围是大于1的范围，请添加HAVING COUNT(*) > your_desired_minimum。

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