MySQL语句转SQLite语句

CREATE TABLE `users` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `username` VARCHAR(50) NOT NULL,
  `password` VARCHAR(50) NOT NULL
);

CREATE TABLE IF NOT EXISTS users (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  username TEXT NOT NULL,
  password TEXT NOT NULL
);

INSERT INTO `users` (`username`, `password`) VALUES ('admin', '123456');

INSERT INTO users (username, password) VALUES ('admin', '123456');

SELECT * FROM `users` WHERE `username`='admin';

SELECT * FROM users WHERE username='admin';

UPDATE `users` SET `password`='654321' WHERE `username`='admin';

UPDATE users SET password='654321' WHERE username='admin';

DELETE FROM `users` WHERE `username`='admin';

DELETE FROM users WHERE username='admin';

CREATE INDEX `username_index` ON `users` (`username`);

CREATE INDEX IF NOT EXISTS username_index ON users (username);