mysql - 组合字段时获取计数

Question

编辑：我改变了桌子。请参阅更新表：

在我的示例表中

post            status      
-------------   -------------
post1           delivered
post2           undelivered
post3           delayed
post4           delivered
post5           undelivered

是否可以在单个查询中获得组合delivered的数量和undelivered+数量？delayed

像这样：

post            status      
-------------   -------------
delivered       2
undelivered     3

Answer 1

SELECT
    SUM(IF(status = 'delivered', 1, 0)) as `delivered_count`,
    COUNT(postid) as `all_count`
FROM
    table

应该可以正常工作。这个帐户只有存在delivered和undelivered状态 - 如果还有更多，但您仍然只想计算这两个，您可以执行以下操作：

SELECT
    SUM(IF(status = 'delivered', 1, 0)) as `delivered_count`,
    SUM(IF(status = 'delivered' OR status = 'undelivered', 1, 0)) as `all_count`
FROM
    table

如果你想单独计算delivered，undelivered你可以使用GROUP BY：

SELECT
    COUNT(postid),
    status
FROM
    table
WHERE
    status IN ('delivered', 'undelivered')
GROUP BY
    status

Answer 2

假设delivered、undelivered和delayed是唯一可用的状态，

SELECT  SUM(CASE WHEN status = 'delivered' THEN 1 END) `delivered`,
        SUM(CASE WHEN status <> 'delivered' THEN 1 END) `delayed + undelivered`
FROM    tableName

• SQLFiddle 演示

输出

╔═══════════╦═══════════════════════╗
║ DELIVERED ║ DELAYED + UNDELIVERED ║
╠═══════════╬═══════════════════════╣
║         2 ║                     3 ║
╚═══════════╩═══════════════════════╝

根据您的编辑，您希望它有多行，

SELECT  CASE WHEN status = 'delivered' THEN 'delivered'
                  ELSE 'undelivered'
        END post,
        COUNT(*) totalCount
FROM    tableName
GROUP   BY CASE WHEN status = 'delivered' THEN 'delivered'
                  ELSE 'undelivered'
           END

• SQLFiddle 演示

输出

╔═════════════╦════════════╗
║    POST     ║ TOTALCOUNT ║
╠═════════════╬════════════╣
║ delivered   ║          2 ║
║ undelivered ║          3 ║
╚═════════════╩════════════╝

Answer 3

如果您只有三个状态，并且您想要一行包含已交付商品的数量，而另一行包含未交付+延迟商品的数量，您可以使用以下查询：

SELECT
  CASE WHEN status = 'delivered' THEN status
       ELSE 'undelivered+delayed' END status,
  COUNT(*) cnt
FROM
  yourtable
GROUP BY
  CASE WHEN status = 'delivered' THEN status
       ELSE 'undelivered+delayed' END

Answer 4

SELECT COUNT(*)
FROM table
GROUP BY status = 'delivered'
ORDER BY status = 'delivered' DESC

这将导致

count of delivered
count of everything else