Create new column with Existing value on other column in MySQL

Avi

I have start_date(varchar) column and i want to add new column duplicate_date(date) with values of start_date column

Avneeesh

Step 1: Add new Column
ALTER TABLE long_holiday ADD (duplicate_date DATE);
Step 2: Update new Column with existing value
UPDATE long_holiday SET duplicate_date = STR_TO_DATE(start_date , '%d-%m-%Y');