Oracle SQL to change column type from number to varchar2 while it contains data

Question

I have a table (that contains data) in Oracle 11g and I need to use Oracle SQLPlus to do the following:

Target: change the type of column TEST1 in table

Answer 1

Add new column as varchar2, copy data to this column, delete old column, rename new column as actual column name:

ALTER TABLE UDA1
ADD (TEST1_temp  VARCHAR2(16));

update UDA1 set TEST1_temp = TEST1;

ALTER TABLE UDA1 DROP COLUMN TEST1;

ALTER TABLE UDA1 
RENAME COLUMN TEST1_temp TO TEST1;