加入还是子查询？

Question

我有一个 MySQL table 记录了各种网站上使用的插件标题，包括版本号。例如：

    AddonName | Website ID | Version

    ZZZ         1           3.3
    ZZZ         2           3.4
    ZZZ         3           3.4
    ZZZ         4           3.1
    YYY         1           1.1
    YYY         2           1.1
    YYY         3           1.1
    YYY         4           1.2

我想创建一个查询，列出一个不同的 AddonName 列表，其中包含总数的详细信息、使用最新版本的所有网站的数量以及使用过时版本的所有网站的数量。

即：

    Name | Total Addons | Up to Date | Out of Date
    ZZZ    4              2            2
    YYY    4              1            3

我不知道如何返回此类数据，尽管信息就在那里。我尝试使用 JOIN 查询，但没有成功。

如果它有助于简化事情，我可以将 'latest' 枚举字段添加到 table，以便在导入时将行标记为 up-to-date 或 out-of-date .

Answer 1

尝试：

SELECT your_table.AddonName,
   COUNT(`Website ID`),
   COUNT(IF(Version = your_table_max.max_version, 1, NULL)) AS `Up to Date`,
   COUNT(IF(Version <> your_table_max.max_version, 1, NULL)) AS `Out of Date`
  FROM your_table
    INNER JOIN (SELECT MAX(Version) as max_version, AddonName
                  FROM your_table group by AddonName) your_table_max
    ON your_table_max.AddonName = your_table.AddonName
  GROUP BY your_table.AddonName;

Answer 2

假设最新版本来自最后一列：

select t.name, count(*) as TotalAddons,
       sum(t.version = tt.maxv) as UpToDate,
       sum(t.version <> tt.maxv) as OutOfDate
from t join
     (select name, max(version) as maxv
      from t
      group by name
     ) tt
     on t.name = tt.name
group by t.name;

这会计算子查询中每个名称的最大版本号。然后它将该信息用于外部聚合。

这假设版本是一个数字。如果是字符串（所以1.10 > 1.2），那么类似的做法是：

select t.name, count(*) as TotalAddons,
       sum(t.version = t.maxv) as UpToDate,
       sum(t.version <> t.maxv) as OutOfDate
from (select t.*,
             (select version
              from t t2
              where t2.name = t.name
              order by length(version) desc, version desc
              limit 1
             ) as maxv
      from t
     ) t
group by t.name;

当然，这也适用于数字。

Answer 3

添加 Latest table 后，请尝试以下操作（在插入您的 table 名称后）

select 
  AddonName as Name, 
  count(*) as TotalAddons,
  count(case TableName.Version when Latest.LatestVersion 
    then 1 else null end) as UpToDate,
  TotalAddons-UpToDate as OutOfDate

from TableName join Latest 
  on TableName.AddonName = Latest.AddonName 
group by AddonName

Answer 4

假设最大值为最新版本。

试试这个：

select t1.AddonName,
count(*) as total_Addon,
sum(case when t1.version=t2.version then 1 else 0 end) as up_to_date,
sum(case when t1.version!=t2.version then 1 else 0 end) as out_of_date
from table1 t1
inner join(
  select AddonName,max(version) as version
  from table1 group by AddonName
)t2 on t1.AddonName=t2.AddonName 
group by t1.AddonName

Answer 5

试试这个，这将解决您的问题。

select AddonName,count(AddonName) as countAdd,(select count(Version)from test1 as t where  t.AddonName = test1.AddonName and t.Version = max(test1.Version)),(select count(Version) from test1 as t where t.AddonName = test1.AddonName and t.Version = min(test1.Version))from test1 GROUP BY AddonName;

Answer 6

WITH cte
AS
(
    SELECT t.AddonName, MAX(t.Version) AS latest_version 
    FROM Table1 t 
    GROUP BY t.AddonName 
)
SELECT t.AddonName, COUNT(t.WebsiteID) AS total_addons,
SUM
(
    CASE WHEN t.version = cte.latest_version 
    THEN 1 ELSE 0 END
) AS up_to_date,
SUM
(
    CASE WHEN t.version <> cte.latest_version 
    THEN 1 ELSE 0 END
) AS out_of_date
FROM Table1 t 
JOIN cte ON t.AddonName = cte.AddonName 
GROUP BY t.AddonName

加入还是子查询？

Join or SubQuery?

mysql

join

subquery

correlated-subquery