Oracle - ALTER TABLE - Delete a Column in Oracle

ALTER TABLE - Delete a Column in Oracle

Q

How To Delete a Column in an Existing Table in Oracle?

✍: FYIcenter.com

A

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.

⇒Understanding SQL DDL Statements for Oracle

⇒⇒Oracle Database Tutorials

2020-02-20, 742👍, 0💬

ALTER TABLE - Add a New Column in Oracle
How To Add a New Column to an Existing Table in Oracle? 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> CREA... 2020-02-29, 822👍, 0💬

ALTER TABLE - Delete a Column in Oracle
How To Delete a Column in an Existing Table in Oracle? 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 dep... 2020-02-20, 743👍, 0💬

DROP TABLE Statement in Oracle
How To Drop an Existing Table in Oracle? If you want to delete an existing table and its data rows, you can use the DROP TABLE statement as shown in this script: SQL> connect HR/fyicenter Connected. SQL> CREATE TABLE emp_dept_10 2 AS SELECT * FROM employees WHERE department_id=10; Tabl... 2020-02-20, 717👍, 0💬

CREATE INDEX - Create a Table Index in Oracle
How To Create a Table Index in Oracle? If you have a table with a lots of rows, and you know that one of the columns will be used often a search criteria, you can add an index for that column to in improve the search performance. To add an index, you can use the CREATE INDEX statement as shown in th... 2020-02-20, 668👍, 0💬

All rights in the contents of this web site are reserved by the individual author. fyicenter.com does not guarantee the truthfulness, accuracy, or reliability of any contents.