Question

我如何在MySQL表上进行SELECT，我将为所有行创建一个值为0的列，除了最后一行将标记为1.是否可能？

示例：

真实表：

    +----+----------------------+
    | id | schedule_name        |
    +----+----------------------+
    |  1 | Global Fee Schedule  |
    |  2 | CAT Fee Schedule     |
    |  3 | Daily Fee Schedule   |
    |  4 | Daily Claim Schedule |
    |  5 | Wind/Hail Schedule   |
    |  6 | Daily Claim Schedule |
    |  7 | Daily Claims         |
    |  8 | CAT Fee Schedule     |
    |  9 | Daily Claims         |
    | 10 | Daily Claims         |
    +----+----------------------+

添加了专栏：

    +----+----------------------+-------------+
    | id | schedule_name        | last_column |
    +----+----------------------+-------------+
    |  1 | Global Fee Schedule  |           0 |
    |  2 | CAT Fee Schedule     |           0 |
    |  3 | Daily Fee Schedule   |           0 |
    |  4 | Daily Claim Schedule |           0 |
    |  5 | Wind/Hail Schedule   |           0 |
    |  6 | Daily Claim Schedule |           0 |
    |  7 | Daily Claims         |           0 |
    |  8 | CAT Fee Scedule      |           0 |
    |  9 | Daily Claims         |           0 |
    | 10 | Daily Claims         |           1 |
    +----+----------------------+-------------+

Answer 1

您可以使用最大功能。例如：

select *, id=(select max(id) from YOUR_TAB) as last_column from YOUR_TAB

Answer 2

不确定为什么你需要这样的东西。但是，这是可能的，但不是很容易做到。

创建/插入数据

CREATE TABLE iascat_fee_categories
    (`id` INT, `schedule_name` VARCHAR(20))
;

INSERT INTO iascat_fee_categories
    (`id`, `schedule_name`)
VALUES
    (1, 'Global Fee Schedule'),
    (2, 'CAT Fee Schedule'),
    (3, 'Daily Fee Schedule'),
    (4, 'Daily Claim Schedule'),
    (5, 'Wind/Hail Schedule'),
    (6, 'Daily Claim Schedule'),
    (7, 'Daily Claims'),
    (8, 'CAT Fee Schedule'),
    (9, 'Daily Claims'),
    (10, 'Daily Claims')
;

将last_column标记为1的select查询非常复杂。

选择LIMIT 0,10

SELECT 
   iascat_fee_categories.id
 , iascat_fee_categories.schedule_name
 , IF((max_id_counts.max_sum_id_count + 0)= iascat_fee_categories.id, 1, 0) last_column
FROM (
  SELECT 
   SUM(id_counts.id_count) max_sum_id_count
  FROM (
     SELECT
       COUNT(*) id_count
     FROM 
      iascat_fee_categories
     GROUP BY
      iascat_fee_categories.id 
     LIMIT 0, 10
  ) AS id_counts
) AS max_id_counts
CROSS JOIN 
  iascat_fee_categories
LIMIT 0, 10

<强>输出

    id  schedule_name         last_column  
------  --------------------  -------------
     1  Global Fee Schedule               0
     2  CAT Fee Schedule                  0
     3  Daily Fee Schedule                0
     4  Daily Claim Schedule              0
     5  Wind/Hail Schedule                0
     6  Daily Claim Schedule              0
     7  Daily Claims                      0
     8  CAT Fee Schedule                  0
     9  Daily Claims                      0
    10  Daily Claims                      1

但是如果你想SELECT LIMIT 1,10选择查询会改变。请注意，您还需要将此部分IF((max_id_counts.max_sum_id_count + 0)更新为IF((max_id_counts.max_sum_id_count + 1) 并且包括两个LIMIT语句

并选择LIMIT 2，您需要对IF((max_id_counts.max_sum_id_count + 2)进行更改并且包括两个LIMIT语句

SELECT LIMIT 1,10

SELECT 
   Table1.id
 , Table1.schedule_name
 , IF((max_id_counts.max_sum_id_count + 1)= iascat_fee_categories.id, 1, 0) last_column
FROM (
  SELECT 
   SUM(id_counts.id_count) max_sum_id_count
  FROM (
     SELECT
       COUNT(*) id_count
     FROM 
      iascat_fee_categories
     GROUP BY
      Table1.id 
     LIMIT 1, 10
  ) AS id_counts
) AS max_id_counts
CROSS JOIN 
  iascat_fee_categories
LIMIT 1, 10

<强>输出

    id  schedule_name         last_column  
------  --------------------  -------------
     2  CAT Fee Schedule                  0
     3  Daily Fee Schedule                0
     4  Daily Claim Schedule              0
     5  Wind/Hail Schedule                0
     6  Daily Claim Schedule              0
     7  Daily Claims                      0
     8  CAT Fee Schedule                  0
     9  Daily Claims                      0
    10  Daily Claims                      1

将最后一行标记为MySQL中的一列

2 个答案: