Debugging MySQL pivot row into dynamic number of columns

Question

I recently came across the thread below, and it was very useful in building a dynamic SQL for MySQL.

MySQL pivot row into dynamic number of columns

With that said, I did struggle with trying to debug the statement. Now for the real purpose of this post! To debug, I would run a Select on my variable containing the statement (Select @SQL). Then copy that result from the viewer windows and have the query analyzer review it. Once I did this, development really sped up. I am sure this is known by all the advance pro developers but for any newbies, I hope this help!

My dynamic statement looks like this as a reference.

SET @sql = NULL;
SET @@group_concat_max_len = 50000;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      ' sum(
      case when symbol = ''',
      symbol,
      ''' then pctttlassets end) AS ',
      CONCAT(UPPER(ACode),'_',REPLACE(Symbol, '+', ''))
    )
  ) INTO @sql
from trade_detail this;

SET @sql = CONCAT('SELECT Distinct(main.port_code) as PortCode, ', @sql, ' 
FROM trade_detail main GROUP BY main.Port_Code');

SELECT @SQL;

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;