Oracle alter table modify column Syntax example

http://dba-oracle.com/t_alter_table_modify_column_syntax_example.htm

For complete tips on Oracle alter table syntax, see the book "Easy Oracle Jumpstart".
Oracle provides "alter table" syntax to modify data columns in-place in this form:

alter table

table_name

modify

column_name datatype;

If you are brave you can use a single "alter table" syntax to modify multiple columns:

alter table

table_name

modify

(

column1_name column1_datatype,

column2_name column2_datatype,

column3_name column3_datatype,

column4_name column4_datatype

);

Here are some examples of Oracle "alter table" syntax to modify data columns and note that you can add constraints like NOT NULL:

ALTER TABLE

customer

MODIFY

(

cust_name varchar2(100) not null,

cust_hair_color varchar2(20)

)

;

We can also use Oracle "alter table" syntax in dynamic PL/SQL to modify data columns

BEGIN

SQL_STRING := 'ALTER TABLE '||:TABLE_NAME||' MODIFY '||:COLUMN_NAME||' VARCHAR2(100)';
. . .

END;