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Oracle Tutorials - Delete a Column in an Existing Table

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 Is a Database Table?
  2. How Many Types of Tables Supported by Oracle?
  3. How To Create a New Table in Your Schema?
  4. How To Create a New Table by Selecting Rows from Another Table?
  5. How To Rename an Existing Table?
  6. How To Drop an Existing Table?
  7. How To Add a New Column to an Existing Table?
  8. How To Add a New Column to an Existing Table with a Default Value?
  9. How To Rename a Column in an Existing Table?
  10. How To Delete a Column in an Existing Table?
  11. How To View All Columns in an Existing Table?
  12. How To Recover a Dropped Table?
  13. What Is Recycle Bin?
  14. How To Turn On or Off Recycle Bin for the Instance?
  15. How To View the Dropped Tables in Your Recycle Bin?
  16. How To Empty Your Recycle Bin?
  17. How To Turn On or Off Recycle Bin for the Session?
  18. How To List All Tables in Your Schema?

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