Oracle和Mysql的主要区别

CREATE SEQUENCE seq_name;
CREATE TABLE test_table (
  id NUMBER DEFAULT seq_name.NEXTVAL
);

CREATE TABLE test_table (
  id INT AUTO_INCREMENT PRIMARY KEY
);

SELECT 'Hello ' || 'World' FROM dual;

SELECT CONCAT('Hello ', 'World');

CREATE SEQUENCE seq_name;
SELECT seq_name.NEXTVAL FROM dual;

CREATE TABLE test_table (
  id INT AUTO_INCREMENT PRIMARY KEY
);

WITH dept_avg AS (
  SELECT dept_id, AVG(salary) AS avg_salary FROM employees GROUP BY dept_id
)
SELECT e.name, e.salary
FROM employees e
JOIN dept_avg d ON e.dept_id = d.dept_id
WHERE e.salary > d.avg_salary;

WITH dept_avg AS (
  SELECT dept_id, AVG(salary) AS avg_salary FROM employees GROUP BY dept_id
)
SELECT e.name, e.salary
FROM employees e
JOIN dept_avg d ON e.dept_id = d.dept_id
WHERE e.salary > d.avg_salary;

CREATE OR REPLACE PROCEDURE increase_salary(p_id IN NUMBER, p_amount IN NUMBER) AS
BEGIN
  UPDATE employees SET salary = salary + p_amount WHERE employee_id = p_id;
END;

DELIMITER //
CREATE PROCEDURE increase_salary(IN p_id INT, IN p_amount DECIMAL)
BEGIN
  UPDATE employees SET salary = salary + p_amount WHERE employee_id = p_id;
END //
DELIMITER ;

CREATE TABLE orders (
  order_id NUMBER PRIMARY KEY,
  customer_id NUMBER,
  CONSTRAINT fk_customer FOREIGN KEY (customer_id) REFERENCES customers (customer_id)
);

CREATE TABLE orders (
  order_id INT PRIMARY KEY,
  customer_id INT,
  FOREIGN KEY (customer_id) REFERENCES customers (customer_id)
);

SELECT department_id, LISTAGG(employee_name, ', ') WITHIN GROUP (ORDER BY employee_name) AS employee_names
FROM employees
GROUP BY department_id;

SELECT department_id, GROUP_CONCAT(employee_name ORDER BY employee_name) AS employee_names
FROM employees
GROUP BY department_id;

SELECT * FROM (SELECT employees.*, ROWNUM rnum FROM employees) WHERE rnum BETWEEN 10 AND 20;

SELECT * FROM employees FETCH FIRST 10 ROWS ONLY;

SELECT * FROM employees LIMIT 10, 20;

BEGIN
  -- some operations
EXCEPTION
  WHEN NO_DATA_FOUND THEN
    -- handle error
END;