如果一個查詢不提取數據，則Mysql查詢不能與聯接一起使用

Question

我必須從下面提到的表中找到總庫存和可用庫存。 表結構：

[Inventoryid] [inventory Type ] [issue status] 
1    Mobile   Issued 
2    Tablet   Not Issued 
3    Mobile   Issued 
4    Tablet   Not Issued 

所需的outpot是

[Inventory Type] [Total Inventory] [Available Inventory] 
Mobile   2     0 
Tablet   2     2 

請給我一個同樣的查詢。

Answer 1

SELECT inventoryType, 
     COUNT(*) totalInventory, 
     SUM(issuestatus = 'not issued') available 
FROM tableName 
GROUP BY inventoryType 

• SQLFiddle Demo

Answer 2

select inventory_type , count(*), sum(case when issue_Status = 'not issued' then 1 
else 0 end) as status 
From yourtable 
group by inventory_type 
;