sql server trigger to mysql - mysql

Question

I'm trying to migrate an SQL Server 2012 trigger to MySQL. The trigger helps to create a hierarchical path for a tree of parent-child nodes which looks something like ".level1.level2.level3" and so on. However, I'm having some issues getting it to work. Here is the SQL Sever trigger creation:
CREATE TRIGGER [dbo].[trigger_TiersPath] ON [dbo].[Tiers] AFTER INSERT, UPDATE
AS
BEGIN
-- This trigger will update the hierarchy diagram for the inserted/updated node and all descendants.
IF (UPDATE(ParentID)) -- Ignore updates to other data fields
BEGIN
-- First, all updated nodes will start with the same string: the new hierarchy diagram of the
-- updated/inserted node. Find this first, then use it as the base for all updated values.
DECLARE #newDiagramStart VARCHAR(MAX)
-- Just use a dot if this is the top of the hierarchy. Otherwise, obtain the hierarchy diagram of the new parent.
SELECT #newDiagramStart = ISNULL(Tiers.TierPath, '.') FROM inserted LEFT JOIN Tiers ON Tiers.TierID = inserted.ParentID
-- Append the inserted/updated node ID.
SELECT #newDiagramStart = #newDiagramStart + CAST(TierID AS VARCHAR(MAX)) + '.' FROM inserted
-- Now update the hierarchy diagram for the inserted/updated node and any descendants.
UPDATE NodesDescendants
-- Find the existing hierarchy diagram after the node ID of the inserted/updated node, and append it.
SET TierPath = #newDiagramStart + ISNULL(RIGHT(NodesDescendants.TierPath, LEN(NodesDescendants.TierPath) - LEN(inserted.TierPath)),'')
FROM inserted
INNER JOIN Tiers AS NodesDescendants
ON NodesDescendants.TierID = inserted.TierID -- Update the inserted/updated node.
OR NodesDescendants.TierPath LIKE inserted.TierPath + '%' -- Update all descendants.
END
END
;
So far, this is what I have for the Insert portion of the equivalent MySQL trigger:
DELIMITER //
CREATE TRIGGER trigger_TiersPath
BEFORE INSERT
ON Tiers FOR EACH ROW
BEGIN
DECLARE newDiagramStart LONGTEXT;
CREATE TEMPORARY TABLE IF NOT EXISTS InsTiers
(
TierID VARCHAR(50),
ParentID VARCHAR(50),
OrgID VARCHAR(50),
TierPath VARCHAR(2048),
Active CHAR(1),
CreatedON DATETIME,
CreatedBY VARCHAR(50),
BatchID INT
);
DELETE FROM InsTiers;
INSERT INTO InsTiers VALUES(NEW.TierID, NEW.ParentID, NEW.OrgID, NEW.TierPath, NEW.Active, NEW.CreatedON, NEW.CreatedBY, NEW.BatchID);
BEGIN
-- This trigger will update the hierarchy diagram for the inserted/updated node and all descendants.
IF (1 = 1) then -- Ignore updates to other data fields
-- First, all updated nodes will start with the same string: the new hierarchy diagram of the
-- updated/inserted node. Find this first, then use it as the base for all updated values.
-- Just use a dot if this is the top of the hierarchy. Otherwise, obtain the hierarchy diagram of the new parent.
select IFNULL(Tiers.TierPath,'.') INTO newDiagramStart FROM InsTiers inserted LEFT JOIN Tiers ON Tiers.TierID = inserted.ParentID;
-- Append the inserted/updated node ID.
-- Find the existing hierarchy diagram after the node ID of the inserted/updated node, and append it.
-- Update the inserted/updated node.
SET newDiagramStart = CONCAT_WS('', newDiagramStart, CAST(NEW.TierID AS CHAR), '.');
-- Now update the hierarchy diagram for the inserted/updated node and any descendants.
NEW.TierPath = CONCAT_WS('',newDiagramStart,IFNULL(RIGHT(NULL, CHAR_LENGTH(NULL) - CHAR_LENGTH(NEW.TierPath)),''));
end if;
END;
END;
//
However, this fails due to some syntax error related to both of the CONCAT_WS lines. I just can't see it. I'm open to suggestions to fix this; or even, finding a better approach to achieve the same ends. Unfortunately, I'm stuck with keeping the whole ".level1.level2.level3" type of concatenated path. In my case those "levels" are actually IDs.
Thanks ahead of time.