MySQL alter table查询的正确语法是什么？

Question

我尝试运行以下mysqli调用

$strSQL3=mysqli_query($connection," alter table mark_list add column 'mark' int(2) " ) or die(mysqli_error($connection));

返回错误

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near `mark int(2)` at line 1

Answer 1

单引号（'）表示字符串文字。对象名称（如列）不是字符串 - juts会丢失引号：

$strSQL3 = mysqli_query($connection ,"alter table mark_list add column mark int(2)" ) or die(mysqli_error($connection));

Answer 2

尝试将'mark'更改为标记，如下所示：

    $strSQL3=mysqli_query($connection,
             " alter table mark_list add column mark int(2) " ) 
              or die(mysqli_error($connection));

Answer 3

您只需删除'标记

附近的引号即可

$strSQL3=mysqli_query($connection," alter table mark_list add column mark int(2) " ) or die(mysqli_error($connection));