php - MySQLi CREATE 表查询不工作

Question

$sql = "CREATE TABLE comments 
(
ID INT NOT NULL AUTO_INCREMENT,
PosterName VARCHAR(32),
Title VARCHAR(32),
Content VARCHAR(500)
)";
$con->query($sql);

没有错误，连接数据库成功。有谁知道为什么它不起作用？

Answer 1

您应该已经看到该语句的错误:

Incorrect table definition; there can be only one auto column and it must be defined as a key:

---

auto_increment 列必须在其上有一个UNIQUE索引，或者更一般地说是PRIMARY KEY:

$sql = "CREATE TABLE comments 
(
ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
PosterName VARCHAR(32),
Title VARCHAR(32),
Content VARCHAR(500)
)";