ORA-01439: COLUMN TO BE MODIFIED MUST BE EMPTY TO CHANGE DATATYPE

Hi,

Let’s assume that we want to change a column type(number to varchar2 for example).
Our table is table1.

create table table1(a number);
insert into table1 select 333 from dual;
commit;
--1 row(s) inserted
alter table table1 modify a varchar2(20);
ORA-01439: column to be modified must be empty to change datatype

So, you must empty table(or column) and then alter table..

let’s copy our table data, that’s less confusing..

create table table2 as select * from table1;
truncate table table1;
alter table table1 modify a varchar2(20);
insert into table1 select * from table2;
commit;
--1 row(s) inserted


try and pray 🙂