Mysql : replace special characters or any words in perticular column in UPDATE statement

Replace # symbol with empty in the given column.
 

SET SQL_SAFE_UPDATES = 0;

update table_name set col_name = replace (col_name,'#','');

Add - Remove Column in MongoDB

// add new column and with default value
db.order.update({}, {$set: {"status": 'NEW'}},{multi:true})

//remove a column
db.order.update({}, {$unset: {"status": ''}},{multi:true})