QUERIES in Oracle

ORACLE QUERIES
Select, Insert, Update, Delete, Drop, Alter table, and Create are the few queries among many that can be executed in an Oracle database.

Oracle Select Query:
Uses: To fetch records from the database.

Syntax: To select records from a table.

SELECT * from table_name;  

Example:

SELECT * from students;

Oracle Insert Query:
Uses: To insert records into a table.
Syntax:

INSERT into table_name VALUES(value1, value2, .. valuen);  

Example:

INSERT into students VALUES(10, 'Joy', 5);

Oracle Update Query:
Uses: To update records of a table.

Syntax:

UPDATE table_name SET column_name1 = value1, column_name2 = value2 WHERE conditions;   

Example:

UPDATE students SET name = 'Joy', age = 5 WHERE id = 10;

Oracle Delete Query:
Uses: To delete records of a table.

Syntax:

DELETE from table_name WHERE conditions;  
 

Example:

DELETE from students WHERE id = 10;

Oracle Truncate Table Query:
Uses: To truncate or remove records of a table but not the structure.

Syntax:

TRUNCATE TABLE table_name;   

Example:

TRUNCATE TABLE students;

Oracle Drop Query: To drop a table or a view.

Syntax: To drop a table.

DROP TABLE table_name;   

Syntax: To drop a view.

DROP VIEW view_name;   

Example: Dropping a table.

DROP TABLE students;

Oracle Create Query:
Uses: To create a sequence, procedure, table, view, or a function.

Syntax: To create a table.

CREATE TABLE table_name
(   
  column_1 data_type [ NULL | NOT NULL ],  
  column_2 data_type [ NULL | NOT NULL ],  
  ...  
  column_n data_type [ NULL | NOT NULL ]  
);  

Syntax: To create a view.

CREATE VIEW view_name AS  
SELECT column_1, column_2, … column_n  
FROM tables  
WHERE view_conditions; 

Example: Creating a table.

CREATE TABLE students
( id number(10) NOT NULL,    
  name varchar2(50) NOT NULL,    
  age number(100));

Oracle Alter Query:
Uses: To add, modify, delete or drop columns of a table.

Syntax: To add columns in a table.

ALTER TABLE table_name   
ADD column data_type  [ NULL | NOT NULL ] ;      

Example: Adding a column in a table.

ALTER TABLE students   
ADD city varchar2(100);