它是varchar而不是var_char

CREATE DATABASE IF NOT EXISTS courses;

USE courses;

CREATE TABLE IF NOT EXISTS teachers(
    id INT(10) UNSIGNED PRIMARY KEY NOT NULL AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL,
    addr VARCHAR(255) NOT NULL,
    phone INT NOT NULL
);

您应该使用SQL工具来可视化可能出现的错误，例如 MySQL Workbench .

You should use a SQL tool to visualize possbile errors like MySQL Workbench.