Single column dynamic pivot - syntax error

Grateful for any guidance. I'm seeing the syntax error below and I can't figure out why. New to MySQL Transforms as my previously relied upon python scripts are to be deprecated.

Objective

To take a single column of dates and turn them into column headers. Once pivoted, row value(s) are irrelevant (they'll be overwritten later).

Desired Result

Input Dataset

The MySQL Dataflow

/Dynamic Reverse Pivot/


CREATE PROCEDURE Pivot()


BEGIN
SET @sql = NULL;


SELECT GROUP_CONCAT(DISTINCT CONCAT('MAX(CASE WHEN dt = ''',dt,''' THEN ''',y,''' ELSE 0) AS ''', dt,''' ')) INTO @sql FROM preformat;


SET @sql = CONCAT('SELECT p.y,', @sql, 'FROM preformat p GROUP BY p.y');


PREPARE stmt FROM @sql;


EXECUTE stmt;


DEALLOCATE PREPARE stmt;


END

The Error