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.

⇒ DROP TABLE Statement in Oracle

⇐ ALTER TABLE - Add a New Column in Oracle

⇑ Understanding SQL DDL Statements for Oracle

⇑⇑ Oracle Database Tutorials

2020-02-20, 3140🔥, 0💬

ALTER INDEX - Rename an Index in Oracle
How To Rename an Index in Oracle? Let's say you have an existing index, and you don't like its name anymore for some reason, you can rename it with the ALTER INDEX ... RENAME TO statement. Here is an example script on how to rename an index: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name... 2020-02-20, 3982🔥, 0💬

Create a New Table with SELECT Statements in Oracle
How To Create a New Table by Selecting Rows from Another Table in Oracle? Let's say you have a table with many data rows, now you want to create a backup copy of this table of all rows or a subset of them, you can use the CREATE TABLE...AS SELECT statement to do this. Here is an example script: &... 2020-02-29, 3799🔥, 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, 3401🔥, 0💬

Create a New Table in Oracle
How To Create a New Table in Oracle? If you want to create a new table in your own schema, you can log into the server with your account, and use the CREATE TABLE statement. The following script shows you how to create a table: >.\bin\sqlplus /nolog SQL> connect HR/fyicenter Connected.... 2020-02-29, 3226🔥, 0💬

Understanding SQL DDL Statements for Oracle
Where to find answers to frequently asked questions on SQL DDL Statements for Oracle? I want to start creating tables. Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on SQL DDL Statements for Oracle. Clear answers are provided with tutorial exercise... 2020-02-29, 3150🔥, 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, 3141🔥, 0💬

Create a New View in Oracle
How To Create a New View in Oracle? You can create a new view based on one or more existing tables by using the CREATE VIEW statement as shown in the following script: CREATE VIEW employee_department AS SELECT e.employee_id, e.first_name, e.last_name, e.email, e.manager_id, d.department_name FROM em... 2020-02-07, 3120🔥, 0💬

What Are DDL Statements in Oracle
What Are DDL Statements in Oracle? DDL (Data Definition Language) statements are statements to create and manage data objects in the database. The are 3 primary DDL statements: CREATE - Creating a new database object. ALTER - Altering the definition of an existing data object. DROP - Dropping an exi... 2020-02-29, 3027🔥, 0💬

Drop an Existing Index in Oracle
How To Drop an Existing Index in Oracle? If you don't need an existing index any more, you should delete it with the DROP INDEX statement. Here is an example SQL script: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT NULL, last_name VARCHAR(80) NOT NULL, birth_date DATE N... 2020-02-20, 2946🔥, 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.