Oracle 12c-如何从一列转换为另一列

Question

I have table 't1' in oracle 12c with one column: 'id1 varchar2 (5 BYTE)'

How to create another column 'id2 number(5,0)' in the same table and copy all the records from id1 column to it?

(values in column 'id1' are numeric by the way)

Answer 1

ALTER TABLE T1 ADD (ID2  NUMBER(5, 0));

and

UPDATE T1 SET ID2 = ID1;

Implicit conversion between VARCHAR2 and NUMBER should handle the type difference, assuming all the characters in ID1 are in the range 0-9.

Best of luck.

Answer 2

First add column in the table

alter table table1 add(id2 number(5,0));

and then just copy existing column in new column

update table1 set id1=id2;