SQL script to convert from varchar to number without losing data

same time converting , in varchar to . for number column

alter table tablename add(dummycolumn number(20,2));

update tablename set dummycolumn = to_number(replace (actualcolumn,',','.'),'9999999999.99');

alter table tablename drop column actualcolumn cascade constraints;

alter table tablename rename column dummycolumn to actualcolumn;

foramtting number according to country currency in java

java.text.NumberFormat.getInstance(Locale.GERMAN)

How to prepare sql insert scripts from excel

=" insert into emp values("&A2&","&B2&","&C2&");"