從不同的表中進行SELECT，並獲得一個結果[mysql] [union]或[join]

Question

你們可以幫我建立一個合適的mysql select並加入以下select的聯接嗎？

我的選擇分別如下所示：

SELECT budget as budget from projects where id =96

SELECT sum(value) as expenses from expenses where project_id =96 

SELECT sum(estimated_hours * t2.man_hour) as estimated from project_has_tasks t1 left join 
users t2 on t1.user_id = t2.id where project_id =96

SELECT sum(TIME_FORMAT(SEC_TO_TIME (time_spent),'%k.%i' )
* t2.man_hour) as time_spent_cost FROM project_has_tasks t1
left join users t2 on t1.user_id = t2.id where t1.project_id ='96'

它們可以正常工作，但我想獲得一種結果，例如：

| budget | expenses  | estimated | time_spent_cost |
____________________________________________________
| 298833 |   24234   |  4434333  |   343434        |   

無論如何，我剛剛建立了一個普通選擇，但它不能正常工作（總和不正確...）

SELECT t1.project_id, t3.budget, 
IFNULL(sum(t4.value),0) as additional_costs, 
IFNULL(sum(estimated_hours)* t2.man_hour ,0) 
as estimated_hours_costs, 
IFNULL(TIME_FORMAT(SEC_TO_TIME 
(sum(t1.time_spent)),'%k.%i' )* t2.man_hour,0) 
as time_spent_cost, NOW() 
FROM project_has_tasks t1 left join 
users t2 on t1.user_id = t2.id left join 
projects t3 on t1.project_id = t3.id 
left join expenses t4 
on t1.project_id = t4.project_id 
WHERE t1.project_id ='96' group by t1.project_id

任何幫助表示贊賞。

Answer 1

當然，總和太高，我假設費用和用戶都返回不止一行，並且對所有行都計算了總和，因此，如果有三個用戶，則估計將是您想要的值的三倍。 假設項目僅返回一行，這可能會更好：

    SELECT t1.project_id, t3.budget, 
           (SELECT sum(IFNULL(t4.value,0))
            FROM expenses t4 
            WHERE t1.project_id = t4.project_id) as additional_costs, 
           sum(IFNULL(t1.estimated_hours* t2.man_hour,0)) as estimated_hours_costs, 
           sum(IFNULL(TIME_FORMAT(SEC_TO_TIME (t1.time_spent),'%k.%i' )* t2.man_hour,0)) as time_spent_cost, 
           NOW() 
    FROM project_has_tasks t1 
    left join users        t2 on t1.user_id    = t2.id
    left join projects     t3 on t1.project_id = t3.id 
    WHERE t1.project_id ='96'
    group by t1.project_id