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

Question

Hi For many days I have been working on this problem in MySQL, however I can not figure it out. Do any of you have suggestions?

Basically, I have a category table wi

Answer 1

The linear way:

I am using a ugly function to create a tree in a simple string field.

/              topic title
/001           message 1
/002           message 2
/002/001       reply to message 2
/002/001/001/  reply to reply
/003           message 3
etc...

the table can be used to select all the rows in the tree order with a simple SQL Query:

select * from morum_messages where m_topic=1234 order by m_linear asc

INSERT is just select the parent linear (and children) and calculate the string as needed.

select M_LINEAR FROM forum_messages WHERE m_topic = 1234 and M_LINEAR LIKE '{0}/___' ORDER BY M_LINEAR DESC limit 0,1  
/* {0} - m_linear of the parent message*/

DELETE is simple as delete the message, or delete by linear all replies of the parent one.