How to transform a MSSQL CTE query to MySQL?

Tony picture Tony · Jan 12, 2012 · Viewed 22.9k times · Source

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

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 

How to 'transform' that query to MySQL ?

Answer

Jon Black picture Jon Black · Jan 12, 2012

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.

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

Generating Depth based tree from Hierarchical Data in MySQL (no CTEs)