How Oracle adds a non-empty column of type CLOB to an empty table

The general step to add a non-empty column is to add a column that can be empty first, and then update that column to a value (such as 0) and finally modify the type

But it's not going to meet the type CLOB. In modify this step times wrong: ora-22296:invalid ALTER TABLE option for conversion of a Long datatype to LOB, so went to the next 22296 Error details: (http://docs . oracle.com/cd/e11882_01/server.112/e17766/e19999.htm#ora-24230)

Cause:an attempt was made to specify ALTER TABLE options which is disallowed during conversion of LONG datatype to L Ob. The only ALTER TABLE options allowed during conversion of a LONG datatype to LOB is the default clause and LOB storage Clau SE for the column being converted to LOB.Action:remove the disallowed options.
Workaround: In update this step: Update tableName Set colname = Empty_clob (); In modify this step: ALTER TABLE TableName modify (colname not NULL); Not the colname clob not NULL, which is different from the general Modify!!!
Example: Alter TABLE Post_info Add (post_content CLOB);
Update Post_info Set post_content = Empty_clob ();
ALTER TABLE Post_info Modify (post_content not NULL);
COMMENT on COLUMN "Dbvop". " Post_info "." Post_content "is
' Notice content ';
commit;---------------In addition: How to change the column syntax of a class that is not NULL CLOB type to NULL: ALTER TABLE tableName modify COLNAME null;

Note: the Empty_blob () and Empty_clob () functions are used to initialize large data type fields.

-----------------How to remove columns with spaces in column names

ALTER TABLE cplnt_workorder drop column "Client_ ISSUE";

-----------------How to modify column names

ALTER TABLE cplnt_workorder rename column "Client_ ISSUE1" to Client_ ISSUE;

http://blog.csdn.net/hjxdreamer/article/details/21230121

How Oracle adds a non-empty column of type CLOB to an empty table