MySQLi LEFT JOIN 查询抛出语法错误

Question

我有两个 table 'lr_users' 和 'lr_ranks' 具有以下 table 结构：

lr_users: user_id(pk), username, rank(fk), job_id(fk), date_joined

lr_ranks: rank_id(pk), name

$qry= mysqli_query($con, "SELECT lr_users.username, lr_users.rank, lr_users.job_id, lr_users.date_joined lr_ranks.name AS rankname FROM lr_users 
    LEFT JOIN lr_ranks ON lr_users.rank = lr_ranks.rank_id")or die(mysqli_error($con));
$rows = mysqli_num_rows($qry);

以上是我的 PHP 生成 'LEFT JOIN' 查询的代码，但是当我运行它时，我得到以下错误：

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 '.name AS rankname FROM lr_users LEFT JOIN lr_ranks ON lr_users.rank = lr_ran' at line 1.

我做错了什么？

Answer 1

语法错误（lr_users.date_joined 前缺少逗号）：

$qry= mysqli_query($con, "SELECT lr_users.username, lr_users.rank, lr_users.job_id, lr_users.date_joined, lr_ranks.name AS rankname FROM lr_users 
    LEFT JOIN lr_ranks ON lr_users.rank = lr_ranks.rank_id")or die(mysqli_error($con));
$rows = mysqli_num_rows($qry);

Answer 2

如果你的代码格式更清晰，就不会出现这种错误：

$query = "
SELECT u.username
     , u.rank
     , u.job_id
     , u.date_joined 
     , r.name rankname 
  FROM lr_users u
  LEFT 
  JOIN lr_ranks r
    ON u.rank = r.rank_id;
";

MySQLi LEFT JOIN 查询抛出语法错误

MySQLi LEFT JOIN query is throwing a syntax error

php

mysql

mysqli

join

left-join