I\'m trying to use the str_to_date function from mysql to convert a TEXT field to a date. Now running:
mysql> select Date from sampleData limit 2; +----------
It looks like you have those doublequotes in there also. When you try to convert it with the doublequotes, you get null.
Try doing:
select str_to_date(REPLACE(Date,'"',''), '%d-%m-%Y') from tab1 sampleData 2;
sqlfiddle demo