如何更新使用演员表身份创建的列

Question

Is there any way to update column which is created with cast

CREATE TABLE test 
(
    num INT IDENTITY(1, 1),
    Token AS 'TK_' + CAST(num VARCHAR(10)),
    name VARCHAR(100)
)

INSERT INTO test VALUES ('data')

If I execute the above query, my result for token column will be "tk_1".

Is it possible to update/insert manually for that "token" column value?

Answer 1

Computed columns are read-only and IDENTITY values cannot be updated. With the computed column, all you can do is indirectly control the value during inserts using IDENTITY_INSERT but that defeats the purpose of using IDENTITY .

If you want to update the value after inserted, make it a regular varchar(13) column and assign the initial value in an insert trigger. That would allow you to update the value to something else after the initial insert.