SQL语句语法中的Php函数

我有以下代码。我希望username接受getUserName函数的值，但是我在与语法作斗争。谁能告诉我正确的答案是什么

$query = "SELECT user FROM users_entity WHERE username = getUserName()";

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可以对句点使用串联：

$query = "SELECT user FROM users_entity WHERE username = '".mysql_real_escape_string(getUserName())."'";

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一定要逃出你的数据

不能将函数的结果直接嵌入字符串中。但是，您可以存储变量的内容：

$username = mysql_real_escape_string(getUserName());
$query = "SELECT user FROM users_entity WHERE username = '$username'";

或者，您可以像这样连接字符串：

$query = 'SELECT user FROM users_entity WHERE username = \'' . mysql_real_escape_string(getUserName()) . '\'';

$query = sprintf("SELECT user FROM users_entity WHERE username = '%s'"
    mysql_real_escape_string(getUserName())
);

不能在字符串中插入（内部字符串替换）PHP函数名

你可能想要更像这样的东西：

$query = 'SELECT user FROM users_entity WHERE username = \'' . mysql_real_escape_string(getUserName()) . '\'';

$query = sprintf("SELECT user FROM users_entity WHERE username = '%s'"
    mysql_real_escape_string(getUserName())
);