Changing the Default Value of a Column : Alter Table « Table « Oracle PL/SQL Tutorial

The default value only applies to new rows added to the table.

SQL> CREATE TABLE myTable (
  2    id INTEGER,
  3    status VARCHAR2(20) DEFAULT 'Order placed' NOT NULL,
  4    last_modified DATE DEFAULT SYSDATE
  5  );

Table created.

SQL>
SQL> desc myTable;
 Name               Null?    Type
 -------------------

 ID                          NUMBER(38)
 STATUS             NOT NULL VARCHAR2(20)
 LAST_MODIFIED               DATE

SQL>
SQL>
SQL> ALTER TABLE myTable
  2  MODIFY last_modified DEFAULT SYSDATE - 1;

Table altered.

SQL>
SQL> desc myTable;
 Name                Null?    Type
 --------------------

 ID                           NUMBER(38)
 STATUS              NOT NULL VARCHAR2(20)
 LAST_MODIFIED                DATE

SQL>
SQL> drop table myTable;

Table dropped.

SQL>

6.3.Alter Table
	6.3.1.	Altering a Table
	6.3.2.	Some of the aspects of a column you can modify using ALTER TABLE
	6.3.3.	Adding a Column
	6.3.4.	ADD initially_created DATE DEFAULT SYSDATE NOT NULL;
	6.3.5.	Changing the Size of a Column
	6.3.6.	Decrease the length of a column
	6.3.7.	Changing the Precision of a Numeric Column
	6.3.8.	Decrease the precision of a numeric column
	6.3.9.	Changing the Data Type of a Column
	6.3.10.	Fill data into new added table column
	6.3.11.	Changing the Default Value of a Column
	6.3.12.	Alter table to add new constraint for new added column
	6.3.13.	ALTER TABLE to DISABLE a CONSTRAINT
	6.3.14.	Alter table to add primary key
	6.3.15.	Alter table to add primary key across more than one columns
	6.3.16.	Dropping a Column
	6.3.17.	New added columns are empty
	6.3.18.	Alter table to add unique with tablespace and storage setting
	6.3.19.	Alter table to add primary key with tablespace and storage setting
	6.3.20.	alter table nologging