Oracle is a relational database management system (RDBMS) originally built by Larry Ellison, Bob Miner, and Ed Oates in the late 70s. It was intended to be compatible with IBM's System R.
|Version 1 (unreleased)||1978-01-01|
|Oracle Version 3||1983-01-01|
|Oracle Version 4||1984-01-01|
|Oracle Version 5||1985-01-01|
|Oracle Version 6||1988-01-01|
SELECT 'Hello world!' FROM dual;
In Oracle's flavor of SQL, "dual is just a convienence table". It was originally intended to double rows via a JOIN, but now contains one row with a
DUMMY value of 'X'.
/* PL/SQL is a core Oracle Database technology, allowing you to build clean, secure, optimized APIs to SQL and business logic. */ set serveroutput on BEGIN DBMS_OUTPUT.PUT_LINE ('Hello World!'); END;
create table MY_table ( what varchar2(10), who varchar2(10), mark varchar2(10) );
insert into my_table (what, who, mark) values ('Hello', 'world', '!' ); insert into my_table values ('Bye bye', 'ponies', '?' ); insert into my_table (what) values('Hey');
select what, who, mark from my_table where what='Hello';
List employees earning more than $50000 born this century. List their name, date of birth and salary, sorted alphabetically by name.
SELECT employee_name, date_of_birth, salary FROM employees WHERE salary > 50000 AND date_of_birth >= DATE '2000-01-01' ORDER BY employee_name;
Show the number of employees in each department with at least 5 employees. List the largest departments first.
SELECT department_id, COUNT(*) FROM employees GROUP BY department_id HAVING COUNT(*) >= 5 ORDER BY COUNT(*) DESC;