sql 組查詢，按順序和限制

Question

我的表結構如下

| id   | cmp      | empid | empname | ttm  
+------+----------+-------+---------+------
|    2 | xyz      | 12    | swap    |    2 
|    2 | xyz      | 12    | sag     |    3
|    2 | xyz      | 14    | azr     |    1 
|    3 | pqr      | 2     | ron     |    2 
|    3 | pqr      | 22    | rah     |    1 
|    3 | pqr      | 32    | pra     |    5 

我已經完成了如下查詢

(select * from test.companies where id = '2' order by ttm desc limit 2)
union
(select * from test.companies where id = '3' order by ttm desc limit 2);

它會給 output 如下

| id   | cmp      | empid | empname | ttm  
+------+----------+-------+---------+------
|    2 | wissen   | 12    | sag     |    3
|    2 | wissen   | 12    | swap    |    2 
|    3 | prolinkd | 32    | pra     |    5
|    3 | prolinkd | 2     | ron     |    2 

但我想要 output 如下

| id   | cmp      | empid | empname | ttm  
+------+----------+-------+---------+------
|    3 | prolinkd | 32    | pra     |    5
|    3 | prolinkd | 2     | ron     |    2
|    2 | wissen   | 12    | sag     |    3 
|    2 | wissen   | 12    | swap    |    2 

表示哪家公司擁有最大 ttm 它將首先顯示

如果有人知道請回復

謝謝

Answer 1

相當丑陋的外觀和丑陋的聲音，但它應該做你想要的。 它使用每條記錄檢索每個公司的“maxttm”，然后在排序中使用它來允許您根據公司的最高 ttm 為其分配優先級。

SELECT * FROM (
    (SELECT *,
        (SELECT ttm FROM test.companies ic WHERE ic.id = oc.id ORDER BY ttm DESC LIMIT 1) AS maxttm
        FROM test.companies oc WHERE id = '2' ORDER BY ttm DESC LIMIT 2)
    UNION
    (SELECT *,
        (SELECT ttm FROM test.companies ic WHERE ic.id = oc.id ORDER BY ttm DESC LIMIT 1) AS maxttm
        FROM test.companies oc WHERE id = '3' ORDER BY ttm DESC LIMIT 2)
) AS myunion ORDER BY maxttm, id;

PS。 感謝 inti 我無恥地以此為基礎的查詢。

Answer 2

我認為這會起作用：

SELECT * FROM (

    (select * from test.companies where id = '2' order by ttm desc limit 2)
    union
    (select * from test.companies where id = '3' order by ttm desc limit 2)

) as myunion ORDER BY ttm;

得到你需要的東西，並通過 ttm 訂購。

Answer 3

select * 
from test.companies 
where id in ('2','3') 
and ttm > 1
order by ttm desc, id