oracle add column

1ALTER TABLE table_name 
2ADD column_name data_type constraint;
3

1ALTER TABLE tablename MODIFY columnname varchar2(100)

1-- ALTER TABLE <table> ADD <column> <type>  <constraint>;
2ALTER TABLE members ADD age NUMBER;
3ALTER TABLE members ADD birth_date DATE NOT NULL;
4ALTER TABLE members ADD registering DATE DEFAULT sysdate;
5ALTER TABLE members ADD member_id NUMBER UNIQUE;

1ALTER TABLE table_name
2  ADD column_name column_definition;

1ALTER TABLE table_name 
2	ADD column_name data_type constraint;