按 mysql 中的参考值划分行

Question

请帮助我。

原始数据如下：

uid | id | value | 
1   |  a |   389 |
2   |  b |   201 |
3   |  c |   170 |

if....当参考值为'200'时

怎么弄成这样的？

mysql..

no| uid | id | value | cut 
1 |  1  |  a |   200 | 200
2 |  1  |  a |   189 | 200
3 |  2  |  b |   200 | 200
4 |  2  |  b |     1 | 200
5 |  3  |  c |   170 | 200

帮帮我！！！

Answer 1

考虑编写一个存储过程，而不是完全在 SQL 中或仅在 select table 中的行中执行所有操作，并在 php 中执行以下操作：

据我了解，您正在寻找这个：

no = 1
For each row in the result set
    for i = 0 to int(value/cut)
        output the row with value set to cut
        no += 1
    output the row with value set to mod(value, cut)
    no += 1

Answer 2

如果您使用的是 MySQL 8 或更高版本，递归 CTE 可以提供帮助：

CREATE DATABASE test;
USE test;
CREATE TABLE TestData (uid INTEGER, id VARCHAR(8), value INTEGER);
INSERT INTO TestData VALUES (1, 'a', 389);
INSERT INTO TestData VALUES (2, 'b', 201);
INSERT INTO TestData VALUES (3, 'c', 170);
INSERT INTO TestData VALUES (4, 'd', 550);

-- Set up an auto-incrementing row number
SET @row_num = 0;
WITH RECURSIVE cte (uid, id, value, remainder) AS (
  -- start with a copy of the table, but adding another column for the value that is at most 200
  SELECT a.uid, a.id, LEAST(a.value, 200), a.value AS "remainder" FROM TestData a
  UNION
  -- repeatedly select from the previous result set, meanwhile decrementing the "remainder" column
  SELECT uid, id, LEAST(remainder - 200, 200), remainder - 200 FROM cte WHERE remainder > 200
)
-- select the actual data that we care about
SELECT (@row_num := @row_num + 1) AS no, uid, id, value, 200 AS "cut" FROM cte ORDER BY id, value DESC;

结果如下 table：

no | uid | id | value | cut
1  |  1  |  a |  200  | 200
2  |  1  |  a |  189  | 200
3  |  2  |  b |  200  | 200
4  |  2  |  b |    1  | 200
5  |  3  |  c |  170  | 200
6  |  4  |  d |  200  | 200
7  |  4  |  d |  200  | 200
8  |  4  |  d |  150  | 200

Answer 3

这个怎么样：

SET @row_num = 0;

SELECT (@row_num := @row_num + 1) AS "no",uid,id,valueA, "200" as cut FROM
(SELECT uid,id,IF(valueA/200 > 1,200,valueA) AS "valueA" FROM tableA UNION ALL
SELECT uid,id,IF(valueA/200 > 2,200,valueA-200) AS "valueA" FROM tableA UNION ALL
SELECT uid,id,IF(valueA/200 > 3,200,valueA-400) AS "valueA" FROM tableA) a 
WHERE valueA > 0
ORDER BY uid,id,valueA DESC;

如果valueA除以200等于大于1，则return200，否则只returnvalueA的内容。这是 UNION ALL 查询中的第一个语法。

第二个我添加了另一个条件，好像 valueA 除以 200 不等于大于 2，它将 return valueA-200。您可以尝试执行 UNION ALL 查询以查看结果。

这不是最好的方法，我相信有更好的解决方案，但我使用这种方法让它工作。您可以将其用作临时解决方案或至少给您一些想法。

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