How To Add a New Column to an Existing Table

Q

How To Add a New Column to an Existing Table? - Oracle DBA FAQ - Understanding SQL DDL Statements

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A

If you have an existing table with existing data rows, and want to add a new column to that table, you can use the ALTER TABLE ... ADD statement to do this. Here is an example script:

SQL> connect HR/fyicenter
Connected.

SQL> CREATE TABLE emp_dept_110 
  2  AS SELECT * FROM employees WHERE department_id=110;
Table created.

SQL> ALTER TABLE emp_dept_110 ADD (vacation NUMBER);
Table altered.

SQL> SELECT first_name, last_name, vacation 
  2  FROM emp_dept_110;
FIRST_NAME           LAST_NAME                   VACATION
-------------------- ------------------------- ----------
Shelley              Higgins
William              Gietz

This SQL script added a new column called "vacation" to the "emp_dept_110" table. NULL values were added to this column on all existing data rows.

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