如何将 MSSQL CTE 查询转换为 MySQL?

2021-11-20 00:00:00 common-table-expression mysql sql-server adjacency-list

在我的 MySQL 架构中，我有 category(id, parentid, name) 表

in my MySQL schema, I have the category(id, parentid, name) table

在 MSSQL 中，我有那个 CTE 查询(为提供的类别 ID 自下而上构建类别树:

In the MSSQL, I have that CTE query (to build a category tree from the bottom up for a supplied category ID:

with CTE (id, pid, name) 
as
(
    select id, parentid as pid,name
    from category
    where id = 197
      union all
        select CTE.pid as id , category.parentid as pid, category.name
        from CTE 
          inner join category 
            on category.id = CTE.pid
 )
 select * from CTE

如何将该查询转换"为 MySQL?

How to 'transform' that query to MySQL ?

推荐答案

遗憾的是 MySQL 不支持 CTE(通用表表达式).这是早就应该的 IMO.通常，您可以只使用子查询，但这个特殊的 CTE 是递归:它在查询中引用自身.递归 CTE 对于分层数据非常有用，但同样:MySql 根本不支持它们.您必须实现一个存储过程才能获得相同的结果.

Unfortunately MySQL doesn't support CTE (Common Table Expressions). This is long overdue IMO. Often, you can just use a subquery instead, but this particular CTE is recursive: it refers to itself inside the query. Recursive CTE's are extremely useful for hierarchical data, but again: MySql doesn't support them at all. You have to implement a stored procedure to get the same results.

我之前的回答应该提供一个很好的起点:

A previous answer of mine should provide a good starting point:

从 MySQL 中的分层数据生成基于深度的树(无 CTE)>

相关文章