1 . 應用場景

每一個union all 的結果單獨排序， union all 之後進行分頁

2. union all order by 單個語句寫法

SELECT
    * 
FROM
    (
SELECT
    id,
    NAME,
    type,
    create_time AS edit_time,
    data_update AS data_up,
    is_delete 
FROM
    v_dataset 
WHERE
    id IN ( 287, 347, 363 ) 
ORDER BY
    data_up DESC 
    ) AS
 
 b

3. sql

SELECT
    * 
FROM
    (
    (
SELECT
    * 
FROM
    (
SELECT
    f.id,
    f.name,
    f.create_time,
    d.create_time AS edit_time,
    d.data_update AS data_up,
    group_concat( d.id ORDER BY d.update_time DESC ) AS DATA 
FROM
    `v_folder_dataset_relation` `r`
    LEFT JOIN `v_dataset`
 
 `d` ON `r`.`dataset_id` = `d`.`id`
    JOIN `v_folder` `f` ON `r`.`folder_id` = `f`.`id` 
WHERE
    `r`.`is_delete` = 0 
    AND `r`.`create_by` = 441 
    AND ( `d`.`is_delete` = 0 OR ( `d`.`is_delete` IS NULL ) ) 
GROUP BY
    `r`.`folder_id` 
ORDER BY
    create_time DESC 
    ) AS a 
    ) UNION ALL
 

    (
SELECT
    * 
FROM
    (
SELECT
    id,
    name,
    type,
    create_time AS edit_time,
    data_update AS data_up,
    is_delete 
FROM
    v_dataset 
WHERE
    id IN ( 287, 347, 363 ) 
ORDER BY
    data_up DESC 
    ) AS b 
    ) 
    ) AS c 
    LIMIT 0,
    9