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Oracle Tutorials - ALTER TABLE - Delete a Column

By: FYIcenter.com

(Continued from previous topic...)

How To Delete a Column in an Existing Table?

If you have an existing column in a table and you need that column any more, you can delete it with ALTER TABLE ... DROP COLUMN statement. Here is an example SQL script:

SQL> CREATE TABLE emp_dept_90 
  2  AS SELECT * FROM employees WHERE department_id=90;
Table created.

SQL> SELECT last_name FROM emp_dept_90;
LAST_NAME                
-------------------------
King                     
Kochhar                  
De Haan                  

SQL> ALTER TABLE emp_dept_90 DROP COLUMN last_name;
Table altered.

SQL> SELECT last_name FROM emp_dept_90;
ERROR at line 1:
ORA-00904: "LAST_NAME": invalid identifier

As you can see the column "last_name" is gone.

(Continued on next topic...)

  1. What Are DDL Statements?
  2. How To Create a New Table?
  3. How To Create a New Table by Selecting Rows from Another Table?
  4. How To Add a New Column to an Existing Table?
  5. How To Delete a Column in an Existing Table?
  6. How To Drop an Existing Table?
  7. How To Create a Table Index?
  8. How To Rename an Index?
  9. How To Drop an Existing Index?
  10. How To Create a New View?
  11. How To Drop an Existing View?

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