ALTER TABLE tableName CHANGE `oldcolname` `newcolname` datatype(length); (you can remove the backticks if it doesn't work)
ALTER TABLE table_name RENAME COLUMN old_name TO new_name;
ALTER TABLE tableName RENAME COLUMN "oldcolname" TO "newcolname" datatype(length);
alter table product change price price_kg float;
ALTER TABLE tableName CHANGE `oldcolname` `newcolname` datatype(length);