mysql - 在 mysql 或 Mariadb 中转换查询

Question

我需要将以下查询从 SQL Server 2012 转换为 MySQL，我没有 SQL Server 转录经验，所以我发现很难弄清楚。

表格详细信息，

create table T
(
 Id int primary key,
 ParentId int,
 Name varchar(10),
 ProductCount int
);

insert into T values
(1, -1, 'Cars',    0),
(2, -1, 'Bikes',   1),
(3,  1, 'Ford',    10),
(4,  3, 'Mustang', 7),
(5,  3, 'Focus',   4);

   create index IX_T_ParentID on T(ParentID) include(ProductCount, Id);

Sql Server 查询，

with C as
(
select T.Id,
     T.ProductCount,
     T.Id as RootID
 from T
 union all
 select T.Id,
     T.ProductCount,
     C.RootID
 from T
 inner join C 
  on T.ParentId = C.Id

 )
select T.Id,
   T.ParentId,
   T.Name,
   T.ProductCount,
   S.ProductCountIncludingChildren
from T
inner join (
         select RootID,
                sum(ProductCount) as ProductCountIncludingChildren
         from C
         group by RootID
         ) as S
 on T.Id = S.RootID
 order by T.Id
 option (maxrecursion 0);

我从未像 SQL 中那样使用过 include、option 和 x

Answer 1

此查询是可移植的，除了查询提示选项(maxrecursion 0)；:

with C as
(
select T.Id,
     T.ProductCount,
     T.Id as RootID
 from T
 union all
 select T.Id,
     T.ProductCount,
     C.RootID
 from T
 inner join C 
  on T.ParentId = C.Id

 )
select T.Id,
   T.ParentId,
   T.Name,
   T.ProductCount,
   S.ProductCountIncludingChildren
from T
inner join (
         select RootID,
                sum(ProductCount) as ProductCountIncludingChildren
         from C
         group by RootID
         ) as S
 on T.Id = S.RootID
 order by T.Id

从MySQL 8.0开始支持公共(public)表表达式。