SQL statements related to modifying the table structure in Oracle 9i

SQL statements related to modifying the table structure in Oracle 9i
1. Add a column:
Alter table table name Add (column name data type );
For example:
Alter table emp add (weight number (38,0 ));

2. Modify the Data Type of a column (generally, the length is limited. There are many restrictions when you change it to a different type)
Alter table table name modify (column name data type );
For example:
Alter table emp modify (weight number (3, 0) not null );

3. Rename the column:
Alter table table name rename column current column name to new column name;
For example:
Alter table emp rename column weight to weight_new;

4. delete a column:
Alter table Table Name drop column name;
For example:
Alter table emp drop column weight_new;

5. rename a table:
Alter table current table name Rename to new table name;
For example:
Alter table bouns Rename to bonus_new