You can change the expression used in a computed column with the ALTER TABLE statement. The following statement changes the expression that a computed column is based on.

ALTER TABLE table-name
ALTER column-name
SET COMPUTE ( new-expression );

The column is recalculated when this statement is executed. If the new expression is invalid, the ALTER TABLE statement fails.

The following statement stops a column from being a computed column.

ALTER TABLE
table-name
ALTER column-name
DROP COMPUTE;

Existing values in the column are not changed when this statement is executed, but they are no longer updated automatically.